Why did so many 50D owners hate the 60D when it came out? Because they were expecting the 60D to be a 7D with a lower price. When Canon released the 7D it was obviously designed as the upgrade step for 50D owners - a larger upgrade step than we were used to, but still the obvious upgrade.
But some 50D owners refused the 7D as on upgrade option. For them it was just too expensive. What they wanted were the same features, but at the same price as they'd paid for the 50D. So they waited, safe in their belief that a 60D would soon appear with all the goodies of the 7D.
Of course, that was never going to happen, as should have been obvious to anybody with an IQ greater than their shoe size. So when the 60D was released, at a price point that was sensible in the new Canon scheme, these people were most upset. So they went looking for things to complain about.
It soon became plain that unimportant things like image quality were better in the 60D, so that had to be ignored. Instead it was derided for only having 5.3 fps; for having an articulated LCD that would fall off after two days (like all those LCDs on video cameras have been doing for the last decade); for not having MA (when reading fora provides ample evidence that most people have no idea how to use it) and, finally and most risably, that it didn't have a magnesium alloy shell.
Apparently it's not the extra stregth of Mg-alloy that's important (although reading this thread has made me wonder just how strong it really is). No, it's the feel of it! The 60D is a terrible, useless pile of junk because it feels 'plasticky' as opposed to the lovely 'magnesiumy' feel of the 7D
very good article, from a guy who as them all.