They've made it a point to remove anything that could possibly make someone better or worse than another playing the same job (and often same role) due to customization choice.
Except for materia, which has been simplified several times itself, they've removed:
- stat allocation points on level up
- the ability to equip accessories from other roles for different stats
- cross-class abilities
- slots for role actions letting you choose which to set
In related changes that weren't expressly the removal of customization, they've also removed:
- all stances that give any sort of stat or ability trade-off
- several different sub-stats that weren't favorable on gear
- pets actually existing in the world, needing to be controlled, affected by AoEs, etc.
- TP and its ability to be depleted
- MP as an actual stat and all abilities that affect it except for one that's shared by everyone
- Protect, Shell, and Stoneskin
I love job/ability system games, FFV is my favorite in the series, and all the Bravely Default games are fantastic. But I can plainly see this goes against everything they do in FFXIV here.
Edit: I should also mention that one of the reasons they gave for making Blue Mage a silly minigame instead of an actual job was that players might not have the spells others expect them to.