While I agree that I wouldn’t want USB charging on most of my lights, it does have a couple of advantages. You don’t need to bring a separate charger when you travel, and you can use it to charge cells for other lights too.
It’s also good for people that don’t want to deal with the extra hassle of charging cells separately. Most people want to charge things the same way they charge their cell phone: plug it in and forget it. Now, you could argue that’s not a smart way to treat lithium-ion batteries, and I tend to agree. But, as long as the light has a reliable charging circuit, it’s not much different than trusting your other lithium-ion devices to charge properly.
Edit: Oops, sorry, I just noticed the post I am replying to is several months old.