The aesthetic aspect of his action is such a minor point and tbh that is very subjective. I personally find Murali's run up, his bulging of eyes at point of delivery etc to be fascinating. The notion has about the same purchase as "I dislike Murali because I just dislike him".
The aesthetics are important, because it's what leads people to have doubts.
Maybe I wasn't clear, but when I personally describe an action as terrible, I mean it in the context of the bowler potentially chucking it, not how classical etc. it looks. I've no problems with Malinga's action, because it's quite clear that his arm is straight when he delivers it. Botha's action looks suspect, Murali's unfortunately does too.
I'm trying to think of a good example for quick bowlers, I think Shaun Tait's action looks pretty poor at times as well.
As I've said, I'm firmly in the "Murali doesn't chuck it" camp. The man's been through enough biomechanical tests to prove that.
However, his action can still look suspect, and it's why people who aren't as convinced by the evidence out there, or who haven't seen it, might harbour doubts over the legality of it.
edit: Murali's inability to straighten his elbows unfortunately doesn't help how clean his action looks, although it's utterly inconsequential.