Personally I feel they do difficulty in the wrong way in this game.

Mechanically a lot of encounters are difficult enough. Sometimes annoyingly so when you have fights designed to bait you into getting killed on your first run, just so the healers have to chain rez and it "feels" difficult. Other times the mechanics are interesting but don't really hurt much if you fail them.
The issue here is always the same. You go in, get whacked about by mechs on week 1, win anyway, learn the trick to it, then every run after that is pure snoozefest.

On the other hand fights rarely scale in damage taken and dps required. In fact they seem to decrease, Expert Dungeons tickle and 8 man normals can be effortlessly solo healed with oGCD's. And enrage timers simply don't exist outside of EX and above and very rare cases. We don't really need to give Normal complex endgame level one-shot mechanics. I'd just like to see things hit harder and have a moderate dps requirement, so you need to be playing your job semi-correctly and can't afford lots of deaths.

FF14's difficulty is always in mechanics and rarely in playing your job and mechanics are only difficult as long as you don't know the trick, unless they go for sensory overload and combine 3-4 mechanics and a "find the safe spot" puzzle simultaneously.