You know how I know you're gay? You listen to Coldplay.
I don't get the hate at all. Even from the "mediocre and generic" angle, they're less mediocre and generic than a lot of other popular groups that don't get ragged on nearly as much. I guess though you could spin that as them being so mediocre, they're even mediocre in their mediocrity.
Get it, they're gay. As in Coldgay. Because gays suck and being gay sucks and only feggits are gay. Cool people are not gay, but Coldplay is gay, because they suck.