I support this 100%, for several reasons.

1) It would give us another companion besides the Chocobo. My Chocobo is Colibri Pink, and I hate him oh so much.

2) Players would be able to see their retainers/companions use the gear that they have rather than just checking on them every hour or so.

3) Some people (like myself) paid as much attention to their retainer customization as they did their own, yet we only see them very briefly.

4) Lore-wise, we always hear that we should "gather your party of adventurers" to take on harder raids. These are obviously the people we play the game with, but it would be nice to actually have someone representing these mystery adventurers as an NPC.