I agree with you completely. But there's a mindset needed from most people before they make the jump from 'vandal' to 'artist' - or vandal artist! There are a lot of graffiti artists doing fantastic pieces - but it'll always be seen as vandalism.

With Banksy a lot of people (certainly in the UK) don't even think of the vandalism, they jump straight to artist - something they probably wouldn't do for a lot of other graffiti. Why so? Publicity? Celebrity sales? The fact the piece has immediate value?