Banning is such a strong word, though. If a majority of miners would in fact refuse such transactions other smaller miners would start getting a lot of orphans and would be forced to either reduce their blocksize drastically or starts filtering out what goes in to their mined blocks. But that's only if the majority of miners sees that as a good thing for the network and their bottom line, no?

I mean, one of the most beautiful things about bitcoins, and one of the most criticized features of it at the same time is the lack of an appointed central authority, but majority still rules the chain.