So many things to address so let's get started.
when was OB released 5 yrs ago or so? They've had plenty of time to get this right, especially since they're using the same game engine and made several games with it before skyrim. Bugs are to be expected in TES but to have so many major bugs shows poor QA, especially when they have so many resources..this isn't the same little company from 10 yrs ago but they put out the same quality game, lots of content loaded with lots of bugs
Assuming that they were not adding new content your argument would be valid. They are going to allocate so many resources to build the engine or tweak what is there depending on what the case is but ultimately most resources are going to go towards creating the new content for the new game. The size of the company doesn't mean nearly as much as you might think, there is still going to be a ceiling for resources (artists, programmers, etc.) and you can't just throw more money or programmers at a problem to fix it. That can actually make the problem worse considering all these programmers have different styles and different understandings of how the internals work.
Sorry quantity in no way equals quality. Trust me, you'll find each one of those quests you haven't done yet to be as listless and predictable as the ones you have already done.
Fair enough, I agree but I personally don't have the problem with quality or quantity of the game's content. Yes, there is a lot of similarity but that doesn't bother me given that I can choose to opt out of as much of the content as I want.
Skyrim is a beautifull, vast, empty world.
I wouldn't say some 200+ dungeons is exactly empty. You can't walk more than 100 yards without something popping up on screen. You certainly can argue it's not diverse but empty is not the word I would choose to describe it.