I agree completely. It seems that there are only 2 ways to solve this problem:
1. Revise the current estate issue, to allow less nobles to control more space.
2. Find 500 new players for the game.
1 is currently in the works, and the plan that I've seen should make it much, much easier to have wildly different noble populations depending on circumstances without crippling your realm or having a bunch of people with !@#$ty oaths.
2 sounds excellent, and all suggestions are welcome!