I'll probably piss off all sorts of druids by saying this, but aside from resto, every single druid spec is a watered-down, less interesting version of another class and plays nearly the same. Why play Guardian if I could just be a warrior? Why Feral if I have a rogue? Why balance when I could be...well, any other caster?
I really don't get how people main this class. It's like a weaker muddle of a lot of other classes.
Honorable mention goes to combat rogues, enhancement shaman and demonology warlocks post-5.3.
Just so we're clear...Casuals don't post to forums and threaten to quit. They quit the game without a word said and go find other games to play. That's why they're casual. Because they're not invested.
I don't dislike any class, really, but there are some specs that annoy me more than others. For instance, dot-heavy specs. I think it's fine single target, they don't bother me at all then, but when you've got multiple dots and multiple targets...tab-targetting and hitting dots and trying to know which ones are dotted and which are not...no thanks.