Here's another hard-core mech guy saying, "If inexpensive eGos keep you off tobacco and you enjoy them, VAPE ON!"

But there are many reasons I use unkicked mechs. Most experienced mech users just subconsciously increase the draw time as voltage drops, and adjust average vape strength by the resistance of the coils they build.
FWIW, the Joyetech USB eGos operate very similar to them, with voltage dropping along with the charge state. The difference is when plugged into USB (pass-through), they're 4.0V and that's as full as they charge. According to Battery University, that should quadruple the number of charge cycles. With a 1.8Ω coil, they go from about 9W fully charged down to 7W at 3.5V and not much less with a common 2.0Ω LR carto. There are also some "upgrade" eGos that let you switch between 3.3V regulated to unregulated.
While eGos may not be replaceable post-FDA, as long as there are flashlights, there will be batteries. Having a mech, especially an heirloom-quality one, one you can rebuild yourself with easily obtained or fabricated parts, will let you use those batteries. And high-quality RBAs use forever available resistance wire. Of course, these won't matter if you didn't freeze some liquid nic base and it becomes unavailable.