Haven't yet seen this theory thrown around (unless I missed it) but what if the limiting factor is not the power cell --- which is supposed to last two hundred years or whatever ---- but the power ~systems~ of the armor? Like, the power system will overheat and some relay or circuit somewhere will burn out and has to be replaced. The actual power core, once installed as shown in the video, will last forever. But the armor itself can still be limited by being a 200-year old suit of armor (no one is making NEW suits, I imagine), so not only do you have to replace the busted-up right arm and left leg but you have to cobble together some work-around so that the power system doesn't shut down after X minutes of use.
Reading about the way the armor can be damaged in pieces reminded me of a scene from Iron Man 3 (was on TV this past weekend) where Tony Stark had only one glove and one boot on and was awkwardly flying around the room and blasting people. I could just imagine Vault Boy in power armor with one arm busted up, hanging at his side, while he tried to swing a street lamp with his left hand and shield his right side from incoming fire....
I never used power armor myself because I did not care for the bulky look and the (perceived, perhaps) noisy and slow nature of it. I would have loved to wear some skimpy raider armor (Painspike) but that was a bit too weak for practical use. That said, this ~new~ power armor is actually intriguing and I am likely to at least try it out a few times.
If it's limited --- as it should be, if it is as powerful as I'd like it to be ---- then I do worry that it'll sit in my garage, all fixed up and painted pretty and never actually ~used~. There are, I suppose, Vaults or specific areas of town where I might recognize that, hey, that area is TOUGH and I will need an edge! And then I will know to go get the power armor. I'd just hate to think I wore it out wandering the wastes and fighting the odd mole rat and then it runs out of juice (or whatever). In a way, I guess, making it limited use and super powerful will actually ~encourage~ me to use it for specific tough areas, instead of as "everyday wear". Which should make using it a more exhilarating experience.