To be more specific, Bethesda creates the bulk of the world, which is mostly unpolished and has a load of problems. Then the modding community makes changes Bethesda seemed to lazy to do that make the game grade A+ quality.
I just downloaded over 30 mods, most of which provide graphical changes and a few gameplay/combat changes, and the game is now at least 50% as flawed as vanilla because of sharper meshes and textures alone.
Maybe Bethesda should accept volunteers/interns from the mod community when they make Elder Scrolls VI: [insert province here], and release it when the mod community volunteers/interns deem it nearly perfect.
Granted Skyrim was amazing when i first played it on release, but now, without these mods, the game seems ugly in comparison.