I was looking around at some encounters in FF14, and while FF14 is probably the bottom of the barrel (which kind of speaks about how bad things currently are given I still play it) it's not exactly unique in having pointlessly complicated endgame encounters. It's getting to a point where I think you probably have to solve a rubik's cube while fighting a boss and then recite a manuscript. I noticed that a lot of developers have this 'if X is good then X+1 must be better'. If the last boss you did had 5 abilities then surely a boss with 6 abilities is even better. There's basically all kinds of bloat in gaming, but most notably MMORPGs since the "X+1" model is a popular, not to mention easy, way to add new content.
I don't play MMO's -- but no scripted fight/AI is ever going to be genuinely satisfying. They are just disguised grinds pre-empting collect-a-thons. If they get more complex (and really, where else can they take AI fights?), it's only mildly distracting for a bit, but then ultimately unsatisfying again once it become formulaic/routine. Just a grind. There are encounters in Turbine's DDO that include "puzzles" -- variants of Mastermind puzzles. Fun a few times, I guess...then it's just a time sink.
Most developers tend to use HP bloat for content, which is annoying and usually leads to power creep.
I've said it before, but MMO's were done right with Ultima Online - it's all been regressing since then. Plop players down in a game world, and let emergent gameplay grow out of their interaction (economy, pvp, politics, etc). UO's issues were massive technology problems (server boundaries) and listening to crybabies.
Players should power nearly everything in an MMO, PvE is just boring and a dead end.