Elderscrolls has a huge modding history and so many modders have created things past and present that have breathed new life into the games.

I wonder if there is room in an MMO to allow modding of some kind?

It would be great if there was some kind of Greenlight project like steam has .Instead the best mods could be showcased and a player vote select the ones that the dev team could incorporate at a timeline of their choosing.There could even be a seperate beta build of the game where these mods can be tested.

This way Bethesda can have free player made content added to the game.

Even if it was just created quests or new dungeons these mods would fill the gap between official expansions.

It definately would be a first for an MMO to allow player made content to be incorporated into the game.

It could be great way to stop the lvl50 duldrums.

It would be great to hear from a developer if what is possible in a single player game can be aswell incorporated into an MMO.

Not entirely true. You can re-skin (use custom textures) almost anything in Guild Wars 1 for example. It's not officially supported but the devs have confirmed that it's allowed and not considered hacking

The only way for someone to "mod" an MMORPG would be to either add custom skins to the UI or models, which are on all your PC, but 90% of all the other content is in the server so you can't really mod it.

its an MMO still with their own servers, steam has nothing to do with TESO. (in some cases its a good thing).

any addon that is made for TESO and played by one player, basicly is there for every player.

so its a bit problematic to make it so that everyone likes the player made content in question.

Mods are more of a single player experience boosters (more quality to the game and replayability). => Oblivion => Skyrim style.