I'm not a big user of Facebook, but I think people are over-reacting.
1. svck it up. Facebook is hugely popular. It's natural for Skyrim players to want to share their characters. What better way to do that than through the existing infrastructure?
2. The only way this could be bad is if it is intrusive. But there's no reason to think that. Indeed, it is more likely than not that it won't be intrusive. Bethesda can't require you to have a Facebook account to play. So why would playing the game require you to be logged into Facebook?
Facebook is interesting for companies because it allows them to acces your profile and private data.
I personally don't want companies to know everything about me. Some people don't care, that's their choice...
But what ussually happens is that companies will try to encourage you to use facebook. They could for example link a unique set of armor to using facebook-users on skyrim.
I also don't care if that option is in or out, as long as it's 100% optional (as in not obligatory or linked to game content).