I love how just because there will be hats and (possible) trading of hats through steam, everybody thinks it's going to get as bad as tf2 lol.
I highly doubt that.
If anything, most servers already have a hat mod or something so the only difference will be that you gain hats through time played on certain servers or game modes and it's through steam, not some random hat mod. There will probably be an option to have all hats disabled on avatars for certain game modes as well.
Or you'll be able to add it on your avatar and you could just disable avatar changing.