I've gone through it again. But the basic idea of rewards is to be gotten through new steem creation (800 per min), or inflation. We could transform it to be smaller % by giving less to existing owners, but that wouldn't be fair to them and would be opposite what whitepaper says. IMHO it's not too big and it should stay the same especially if u take in consideration effects like a reverse stock split.
Else as I stated in previous posts we would need some other way of rewards sharing to take place. With more users, individual rewards fall down so we might need even more steem to be produced or even bigger inflation.
Even with the current system, one could argue that you have inflation % reduced every day as steem is produced at fixed rate if u don't watch only on a yearly basis.
It's just mine uneducated opinion.