I've noticed several things about the people that despised the T&P episode.
1) Most of them didn't watch the whole thing, got pissed off in the first 5 minutes and turned it off, then came here to tell us how much the whole episode sucked.
2) Those that did watch the whole thing were so pissed off about a) not finding out who cartman's father was, and b) that it was terrance and phillip that they didn't bother *WATCHING* what was going on to get all the jokes.
3) Those people without *SOME* kind of connection to Canada probably missed 80% of the jokes. For instance, most people don't understand that Kraft Macaroni and Cheese (what it's called in the US) is called Kraft Dinner up there, and that lots of canadians seem to have some kind of fetish for this stuff.
If you don't get the jokes, it might seem stupid, then they feel even more stupid because they didn't get the jokes, and they turn that into anger at M&T for making them feel stupid.
It really was a brillian april fools joke. What most people don't understand is that the real joke is the fact that this stuff *IS* funny, just probably not to you.