It contributes too much money to bitcointalk and the crypto economy, and Theymos supports them.  He's stated that he doesn't want to do away with signature campaigns, so that's not going to happen--but he's definitely aware of how bad the problem is, and that's why we got the merit system.

Yes, the altcoin section is probably worst than Bitcoin Discussion and Economics combined.  Last time I visited, it looked like it was the place to be for illiterate bounty spammers (and all of their alt accounts).  They only venture outside Altcoin Discussion when they come to Meta to complain that they're not getting merits.
No, I think it's mostly Altcoin Discussion and Altcoin Speculation.  Those are the worst of the worst.