Environments / The World At large – Making the world feel more alive
1.) More interactive Objects – for example Let me sit in more chairs near tables (Adventurers guild) and various spots around the world
2.) Allow us to have different idle stances in passive mode, like NPCs
3.) Maybe a comment in /check like Bazaar comments (was always nice)
4.) Have the NPC's move around a bit
5.) Voice out as much Dialog as possible
6.) Occasional Mob to Mob interaction
Would be so cool seeing two wolves in the distance fighting or an occasional larger mob eating a smaller mob. Makes you feel like you ARE in the wild. Makes it more real.
Add: Lots of open world content, otherwise the world will feel dead even with these changes because everyone will be in an instance somewhere and making a world feel more alive is by actually being a part of it and not in some random cluster that no one else can visit but your party.

Mob > Mob interaction I recall was from FFXII and XIII which they said they always wanted to do with FFXI, so this is something I definitely expected to see in FFXIV.