it really isn't retconned... the poster who pointed that out to you is right... doesnt matter if it wasnt in the mechanics of the older games, it's in their lore, doesn't matter how they 'treated it' at the time
yeah its way different than any GAME yet, but the lore info on power armor actually does describe it basically as a human shaped vehicle/tank, complete with circuitry, mechanized parts, hydraulics and everything
you can dislike the change, that's totally your call, but you're wrong on the retconning bit of it
this is just the first game to implement the more vehicle-like aspects that have always been in the lore, yes lore going back way before FO4 or Beth even having the franchise at all, all the way back into Black Isle's backyard
so... change in game mechanics? yes and you can totally hate it if you want. retcon of the feel/facts of PA? sorry no, just the first time the mechanics better reflect the lore descrip of PA... that just has to happen as games go forward
shouldn't throw around retconning accusations so wildly, save that for big things like if... say... the entire history start of the NCR was rewritten or something
ex. Skyrim getting rid of item degradation shouldn't start the 'OMG retconning! we riot!' spill, it's just a mechanic change... a lame one, but definitely not a retconned behemoth of changiness (unless your definition of retconning is ANY change, but then pretty much EVERYTHING would be retconned... retconned HUD, animations, retconned hair physics, but i don't think that's what you meant)
retcon usually means something like... altering information regarding the back story of a fictional character/world/concept, regardless of whether the change contradicts what was said before.
FO4 does not do that to PA, it's lore is the same, it's just reflecting what's already been stated in the past better... again you can like it or not, just not a retcon of PA
as for the fuel bit... i think some had the need for mf cells? but most had built in power supply so it likely won't be an issue
I'm sure that won't change your mind at all, cause internetz laws say you can't budge from your opinion after stating it, but yeah
i guess you can hope there's something close to the NCR salvaged PA so you can RP that all PA is like that i guess? that's all i can think of to solve your dislike of it. or mods of course i guess