Then you are talking about paid content in form of DLC straight away. If Valve should hire someone to do this job to go through each mod make sure it isn't conflicting with parts of the game or other mods it would cost them money. Hence to make up for that they would need to sell these mods as DLC. So the question is would you be willing to pay €5for a mod that adds darker dungeouns? then another €5 for a mod that adds a basemant to breezehome? Then another mod that changes the color of certain things, thena mod that gives more quests, then a mod that does this, then a mod that does that...
Just to add to this bit. It all would still require MS and Sony to okay the whole thing and they're not going to want to be left out of the profit pie. So unless they can get a share (ie: the biggest share, despite a lack of costs on their side) of the cash, they're going to just straight out say NO. As they are currently doing anyway.
Looking at my current mod list I have about 15-20 mods running, more will be added later today when I start browsing for more mods. The PC community does have mods and all it's fun things it brings with it, but we also run the risk of various other things. CTD's due to conflicting mods, instability, isses with quests stopping working etc etc. Modding isn't just heaven as you do run the risk of breaking your game. On a PC it's relatively easy to fix tho, you have the windows explorer and you can remove files manually. On a console you don't have the same options. If a game breaks badly, you would risk your savegame, installing the game from scratch etc etc. There is no easy fix just open explorer and remove the files that causing it and edit the ini file.
Very true. The open file structure of the Pc makes troubleshooting much easier. On a console you'd have to hope whatever programs are involved for installing/uninstalling are up to finding ALL the files related to a troublesome mod, or you'll be looking at doing a lot of clearing the cache.
Also, mods are going to take up hard drive space. Small mods, not much. Larger mods, I've seen some take several GB.