Hmm, that is an interesting concept. Perhaps there should be something which 'glues' them all together, however? Some people might not be up for running their own manor/thread. I like the idea, myself, but it could theoretically prove to be a problem/deterrent to some.
I like the idea of nobility or someone with at least enough money to basically be a noble, as this allows freedom to do things, where a simple Plebe would be screwed more or less, unless the player was highly creative.