Why? I see nothing wrong with the this system, the original owner and the state agree to it.

Probably UK is better since a huge estate can make /generate much more income /employment than a 1000 plots of 1.2 acres each.

They have power because they have money. A window washer that is the second cousin of Queen Elizabeth and with a nobility title is just a window washer, barely making ends meet. Now Queen Elizabeth's second cousin with 50,000 acres, a nobility title and two castles is a different thing :)