Sorry, Nosferatus, I think you're missing some points here:
1. A newcomer isn't going to happy spending a week just travelling to a vacant estate. Improving the road and travel time might help a lord attract nobles to the region. Strategically, one can choose to upgrade roads to help the realm's army get to the front easier, or choose not to improve the road and make it harder for the region to be invaded.
2. City/Stronghold/Town usually provides more income for their nobles, this suggestion was intended provides incentive to claim rural estates. I should know, one of my character is lord of the realm's granary, but financially me and my knights are the poorest. Political capital: don't insult the person who feeds you. Unless someone is willing to suggest we abolish non-C/S/T regions or make it a punishment post?
3. The idea was to not defect. If you're in rebellion, what are the chances of you going to the capital to recruit more soldiers to your cause, however just it may be? Balance of power, giving regional lords the opportunity to stand up to their rights, if they so choose, instead of running away. Politically, if you manage to antagonize every other nobles in the realm then you're better off defecting, if you have reasonable grievances, you have the option of making a stand for it. Come to think of it , this also applies to when the realm is split due to invasion or mismanagement of connecting regions, it will only be a stopgap measure but it will be there while the realm rallies to restore the connection.