There is a mod out there that allows you to build your own house. Well not build it but pay for the things it would require, Wouldn't that be absolutely amazing if Bethesda added that in to their next game. Imagine different materials to choose, and to choose where you want your house to be located. I think it would be cool. And another just a side note would be a continuous war between two factions like the Stormcloaks and Imperials placed on a map and make it constant fighting like a battle.

Can I rebuild Winterhold?

I would love to do this but under the compact you cannot.