There is no way I'd playing any X game without mods.
The XRM mod alone is making me put time in Albion Prelude.
Skyrim, it goes without saying, would be much less than what it is without mods.
Not all games will benefit the same from mods. Some games are play and forget(which is fine). But if there is a demand, and the developers can make the tools available, I can't see any reason to discourage modding.
It's one of the major advantages that PC gaming has over consoles.