I agree with you, that a lit switch would look cool. . However, I think a recessed switch, something the E07 and the present D4 lacks, somewhat makes up for the switch not being illuminated. It makes it easy to find the switch and makes it less likely to be accidentally switched on in your pocket, should you forget to lock it out.
This is the one thing that would entice me to buy more D4’s. My current D4’s don’t get used much, primarily because I prefer regulated output.
If the new D4 has higher regulated output and Anduril, I guess I could stop worrying about the FW3A optic debacle.
I don’t think there was much feedback before about a lighted switch being a priority. There was some about aux LED’s.
Also, the current button on the D4 has a pretty good feel as it clicks - much better than the lighted button on the ROT66. I don’t have a Q8 to compare to. Either way, if fitting LED’s on the relatively small button of the D4 adversely affects the feel of the button, I’d vote to keep the better feeling switch.