Canadians tend to like the preclearance at Canadian airports because, worse case scenario, you turn around and go home. Americans don't have that option, and ICE treats us just as badly as Canadians or foreigners. Especially at YYZ, where there is no separate line for US citizens at Immigration.
Also, no one said a thing about showing up at the airport last minute. I said that I need to get there at least 2.5 hours early, instead of an hour or so. That's a big deal, especially if it's an early flight.