Wiggles you make a good point. I agree that the fights might have too many mechanics in them and that they are too punishing if even a few people make mistakes. If I think back to WOW hardmodes, encounters would usually employ a few mechanics, with only end bosses in a dungeon going for multiple mechanics to learn.
If we look at FF14, Titan himself has how many moves? 5 moves, on top of a heart phase? And if you miss any one of the 5 mechanics, it becomes very rapidly hard to recover from unless the rest of the team over gears the content.
From my perspective, I see it as poor design. Getting 1 shot by multiple mechanics does nothing for gameplay value, it just adds annoyances to the players partaking in the encounter. Also it encourages players to become annoyed with others who can't dodge mechanics, and further encourages a split between "elite" players and "non-elite/casual/mechanically poor" players. I don't think its healthy for a game to have players genuinely become frustrated with playing with other members in the player base. It hurts the social aspect of the game.
However, on the flip side of the argument, if these encounters were made even easier than they already are, what else would there be left for players to do? Hundreds if not thousands of players on my server have already cleared Titan, whether that be through their own skill or by being carried by others, I feel that the majority of the playerbase has already entered into the final stages of end game content in the current game. SE probably developed the encounters this way though to increase the lifespan of their game which already is stretched thin in terms of end game content. So in that regard, I can see why encounters are the way they are. Still don't like it though.
Only time can tell if SE will be able to improve the environment and content of their game. With their current design decisions however, they are going to have to churn out a lot of content to keep up with how fast players are consuming it. I have a bad feeling they will continue to employ encounters with 5+ mechanics, aggravating instant death mechanics, and the over use of red zone dodge mechanics which will only serve to frustrate players.