Make the order of bosses not so linear. Like how some of the open area dungeons of WoW(I was thinking Legion, Eye of Azshara) where it is not clear which direction to go and you can skip bosses or do the bosses in a different order.

Lately the dungeons have all been treadmill like, first boss, second boss and third boss. They could make some new dungeons, third boss, first boss and then second boss in that order, or whichever order people would like to run it in.

Just an idea to make some interesting dungeons in FFXIV.