You answered your own question. His game doesn't appeal to a lot of people, including me.
I don't Hate the guy, but i don't like to watch him play. Makes it worse when people say you should support him because he's British
Any player with a primarily defensive game is bound to get more haters because thats how MTF works.
Basically, you're saying MTF is one dimensional .In my opinion, it's just domino effect,people are easily influanced by others ,going manistream like in real life ...Nothing surprising.Disliking someones game is fine , but crude harrassment, insults and stalking is completely different thing.
Murray poor introvert,who doesnt even try to court publicity is an easy target for their mockery, so he's often ridiculed and bullied-again , that happens in real life as well.Nothing surprising.