This is a major suggestion to the development team. Depth is something almost every other MMO has lacked for the last 8 or 9 years. In the world of MMOs, depth is what we see as the little things. Things like housing, mods and most importantly, customization. Sure, questing and raiding are the meat of MMOs, but I personally love to play a game that has so many different things to do. Since the days of olde, Elder Scrolls has soundly demonstrated this, and in my opinion, ESO should be no different.
Some specific suggestions are:
-Player image customization (not cookie cut faces and bodies)
-Housing
-Armor customization (color, warpaint, etc)
-Mod integration (For UI, damage meters, raid assists, etc)
-Full left hand/right hand choice for combat (same as Skyrim)
If anyone else has anything to add, feel free.