Four reasons I'm confident there will be far fewer (unpatched) bugs in Skyrim:
1) Larger team. The Oblivion team was overworked, for example, every dungeon in the entire game was made by one designer. There are 30+ more people on the Skyrim team.
2) Incremental patching. There will be more and more frequent patches that will include annoying little stuff as well as larger quest/game-breakers,
3) Closer dialog with the developers. I know us unofficial guys will be getting as many bugs reports if not more than the Bethesda team, so I'll be starting a bugtracker and have opened a dialog with Bethesda to forward them the vetted, confirmed finds so that they can fix them officially.
4) Streamlining. There's simply less to break with no classes, three stats, and no spellmaking among others.
And, yeah, FO:NV != Bethesda Game Studios.