Let me be perfectly vague; I didn't like 123s in cameras, and I sure as hell don't like them in flashlights!
Boaz, where do you get the 123 for $.21? I need some too. 
While I can't comment on why "people" avoid cr123 lights I can comment on why I don't have any.
When I started my obsession in flashlights most of the brightest and best built options were Alkaline based or later, NiCad so that is what I purchased. The obvious draw backs of both of those power sources led me to move to NiMH batteries for all those D, C, AA and AAA lights. Gradually, lithium primaries became available but I already had a ton of lights and was busy converting my old incans to LEDs and converting over to rechargeable batteries.
So now I have a huge supply of NiMH batteries (and a few chargers), when I'm looking for a new light I look for one that will work with my batteries. If I move over to something that takes a cr123 I will also need to stock a supply of primaries or a few rechargeable and get a charger, simple case of economics.
I have nothing against cr123 lights, last Christmas I purchased 2 Olight T10s for a couple of friends (they loved them) and to tell you the truth, I wouldn't mind having one myself but...(see above). For gifts this Christmas, I made a flock of Mini-Mags using Match's 15 minute Mini-Mag mod, everyone loved them! While cr123 lights can provide impressive amounts of light, the comercial availability of more traditional sized lithium batteries has allowed manufacturers to build equally impressive lights around them.
As soon as I have explored every AA, AAA and D cell light that catches my eye, or that I can build/mod, I will move on to other power sources. There are more than a few that have my attention at this time! The fact that I am at the north side of 50, with two kids starting college I fear that by the time I'm done with my old cell size batteries, the point will be moot. At that time we'll be using supercharged capacitors.
I understand not wanting to buy primaries for junk lights So i understand where Gcbyan is coming from .(cut cut dig dig ) :P
If you have a nice ride them putting premium in it isn't as much of a pain ...
I know that sounds mean like i'm bashing but it's true ..
I bought a zebralight really cheap.. Cheap enough I wasn't gonna pass on it just because it was a cr123light
same with the ex-10 lights and a few more Nitecores SR3 and extreme infinity ..they are nice enough that I realy couldn't care if i ever sold another one .I have hundreds of stupid lights I'd rather sell first ..(So it's not because I want to sell a light )(Does anyone hear me trying to hock the last 12 ex-10's or 2 ezAA's here on BLF??)
Note to self :...... kill Gcbryan
hahaha 
My 2 cents... I bought 10 cr123s for a buck a piece so I have been looking for a nice single 123 light that I can use them in. Most of the budget choices have blinky modes and/or low output. Most of the nicer non-budget choices are either too expensive or do not have the features that I'm looking for.
So in my case it's not the batteries, it's the lights that I can't find the price and features that I want.
I almost pulled the trigger on a SWM V10r XML, but it is brighter on a Li-ion so I would probably never use primaries in it.
The search continues...
I'm really enjoying my new nitecore ex11.2 and my tf flames (16340) batteries just arrived. I only went to this battery size because of this awesome little light. I'll probably order the klarus p1c since none of my other lights use this battery or have a forward clicky. I like the jetbeam but the clip wasn't well thought out on it.
cr123s really don't do much for me, im talking about cr123s not rechargeable versions, they barely power xml lights vs a single double A battery. i have panasonics and battery junction ones, and they do the same. now rechargeable ones, thats a different story, i love those. i love all batteries rated 3.7 volts and rechargeable, i am giving up on the rest, even eneloop and duraloops, lights nowaday require the extra voltage, xml was supposed to be more efficient, but it has a plateau you must first reach, and regular batteries aren't cutting it.
All of the early LED lights I bought (2005-6) ran on CR123. Some of them could be trusted with rechargeables. Some of them couldn't.
The ones that couldn't died.
After 2007 I didn't buy lights that couldn't handle 4.2V.
Less of an issue now than it was 6 years ago. Though my most recent light purchase turned out to be 1.5V or less only. Must ask Manafont if they can source a new driver for me.
I can find AAs and AAAs anywhere that sells batteries, even gas stations in the middle of nowhere have them. Try finding a cr123 at a hillbilly gas station in the boonies when you are out camping and need fresh cells. Ain’t gonna happen. AAs are everywhere and cheap.
Use what you want but cr123s are quickly going to be marginalized since AA lights are very bright now.
Im gonna be an oddball here and say I love my olight i1 ,i like the lightweight brighness and XML in a small package , I tried the aaa and just feels more longer in my pants pocket so I prefer short and stubby ,lol
Now that is my edc , I love others but not for edc 18650 , 26650 and I’m gonna give the ultrfire version of th infamous sipik zoom out 14500 but it’s just because u guys told me to ,lol
I hope to see more nicer 2AA lights...
But if u r out camping shoulnt u be prepared? I probably would have a lot of lights and batteries,just my 2 cents:)
I just don't see the need for them. I don't see any real advantage to them other than I can buy them in retail stores where I have to order 18650s online. I have a Streamlight weapons light that uses cr123 batteries so I have a couple of 12 packs that I bought for that light. I think all my 18650 lights will take cr123 batteries if I need them to do so. I have tried a couple just to make sure they work but I just don't use them. I just prefer 18650 and AA NiMh batteries and the lights that use them. I have thought of buying a small light that uses only one cr123 such as a Quark mini but I really don't need one for any reason. I have a iTP A3 E0S that I carry all the time and I use that almost everyday. It's a light that I use for mostly short stints when I just have to check something out quickly. My S-mini is still small enough to carry comfortably in my shirt or pants pocket if I need more light. What really is the need for a different kind of battery or light?
I love the shortness of it while in my front jeans pocket , opinion r like butt holes ,lol
But if u r out camping shoulnt u be prepared? I probably would have a lot of lights and batteries,just my 2 cents:)
[/quote]
Ideally, yes. I have yet to go on any sort of camping trip when at least one member of the group hasn’t forgotten something. Sometimes it is spare batteries, sometimes, it is a knife or a lighter or something that you just assumed you had but didn’t.
Having lights that take easy to find cells just makes life that much easier. My AA and AAA lights are plenty bright enough for camping that I often use the medium modes so that extra power from the CR123 is more than cut short by the expense and difficulty to obtain nature of the cells.
I have been CR123 free with the exception of my Surefire weapon light for a couple of years now and I have not missed them at all.
One of my all-time favorite flashlights prefers CR123s; the Skyline 1. Runs just fine on an 18650 and the lower output is hardly noticeable but, I still keep a 10-pack on hand for it . . . and my never used 6P.
CR123s and the lights that use them will be around for a long time. Long shelf life and good output will keep them in the hunt for quite a while.
Foy
16340 / CR123A VS 18650
Well I tried cr123a First , back then , not much chop [ Old emitters - single mode ] , + increased current and lower output when compared to 16340 ..
16340 VS 18650 = mostly run time , + a P60 is almost as easy to carry ..
Dont get me wrong , I love some of my 16340 lights [ A20 XM-L ] , my last A20 mod is my favourite , and use it all the time ..
A20 - XM-L emitter - 1.4A 3 mode driver = Well regulated output in a small package , unfortunately , Low run time !
Boaz likes them.
That's reason enough to avoid 'em, right there...
Yes while you can get fairly cheap decent branded CR123 in the US fairly easily, outside the US it's often far more difficult. For example here in NZ you can get the random noname Chinese brands on auction sites although they're still fairly expensive or you can import them yourself. But if you want decent quality CR123 you have to import them from the US which tends to make them expensive if you aren't buying a lot due to shipping charges. So the benefit of primaries is limited compared to AA sized lamps. This means you're left with RCR123, but unless you prefer the size to 18650 or 14500 there's no reason to go with it. Note that AFAIK, a large percentage of the professional lights are sold for things like military and police use in the US, where they buy batteries in large quantities, so the price isn't really an issue.