TES don't have to be ridiculously linear, heck, F3 which was in development BEFORE Oblivion, had better choices, NVegas having great choices.
Why can't they change?
Fallout 3 was in development before Oblivion?
Can I get a source on that please?
Oh wait, I can't, because that is an absolutely false statement.
You have to understand that TES fans have been waiting 5 years for this release, Fallout: New Vegas just came out. We don't want a Fallout set in TES universe.