The problem is these extras waste resources that could be used for much better things. Like more landmass, dungeons, better quests, etc. Bethesda has only so much resources and technical limitations to work with(Xbox 360), so if they add or improve things chances are something has to be dumbed down or removed. These kind of extras are better left to players to mod in.
Adding a dancing/mini-game mechanic isn't going to bog down the system. (EDIT: Forgotten point ->) However, adding more cookie-cutter dungeons, more mundain "go here, collect that, go there, collect this, come back" quests and landmass with little value gameplay value do bog down the system.
I'd rather have miniscule content that makes the game feel living than have more of what I'm all ready getting bored of.
The game was all ready dumbed down and had many interesting little bits removed for the mere reason of a release date. Look at smithing, the lack of any type of spell combining, the Winterhold quests and the town in general... Another great example would be the Giant and the Painted Cow, I believe this was to be an element in the Civil War questlines that was left out and would have been one of the more original and possibly entertaining quests in the entire game, compaired to what we got with that quest line in the end.
Alas, the players should not be expected to mod their games to get enjoyment out of them... That's why I paid money in the first place... So I didn't have to make my own game to play.