I am not very far into the game, and I haven't experienced a whole lot of FF14 dungeon content. However, I agree with the basic premise of your OP. This is a problem in just about every MMO I've played over the years. Trash mobs tend to be boring, especially when you are really good at playing your class/role; and even more so when all party members are good at what they are doing.

Every now and again an interesting boss mechanic will throw you for a loop the first time you run into it, and that's great. Bosses are supposed to be memorable, IMO, and they are supposed to make you work for the victory; that is until you've run the boss so many times you can do it in your sleep, which comes with the territory of grinding for gear.

However, I also would like to see more interesting mechanics implemented in-between bosses. One dungeon I have ran in FF14 that has done this is the Temple of Qarn, where you have to kill the block enemies on the specific tiles. As simple as this was, it broke the monotony of just sprinting to the next boss. Maybe there is more stuff like this in FF14, IDK, I'm not too far into the game yet.

I am a big fan of puzzles and interesting mob mechanics in any game. The first couple of times doing something out of the ordinary can be fun and enjoyable, before we ruin the experience with gear grind... O.o