MK is not a bully, he is just too lazy to find real abuse. Since the MK account has a decent amount of SP he is a nuisance.
Most people are not abusing SBI. Also, Joseph addressed some issues with SBI that were enabling people to abuse it (they were upvoting all SBI posts and getting max upvotes).
Now SBI seems to be working well and I notice a lot less problems with abuse there.
I think downvotes should remain free. They are necessary. Maybe they should cost 10x or 100x the RC, though.