I generally agree, but once you do that you lose most of the properties that make bit torrent so effective.

E.g. if you arrange the network into a tree like that, you need to make sure all nodes are matched appropriately in terms of bandwidth, latency, geography, number of connected nodes. Now you have to somehow the network topology stays good in face of churn and bad peers. Suddenly everything is complicated and not looking very p2p.

Maybe dufferent protocols are possible to manage that, but i think there is a reason why p2p protocols kind of didn't develop much beyond bit torrent.