Skrewdriver and Prussian Blue arent emo and My Chemical Romance isnt a chav band (its closer to emo), what are you talking about
I suppose emo music has a certain integrity to it which chav music generally doesnt. Faux-sentimentality is still sentimentality, sort of. I find most stuff that grew out of hardcore to be repugnant to listen to, but at least they seem to believe in what they're doing, which is more than you can say for most chav music.
edit: on the otherhand, you could argue that chavs have an excuse for liking shit music since theyve been brainwashed by commercialism, whereas emokids have actually managed to seek it out and brainwash themselves.