IMO graffiti is really good, cities should set out areas were graffiti is legal, everyone could go graffiti and wouldnt get in trouble for it. It would keep the cities much more cleaner. And from there if you wanna go see some artwork without going to a shitty gallery go down to the graffiti spot
The idea of graffiti...in most cases, is to rebel.
Conforming to a legal wall wouldn't appeal to people.
It's kinda like an analogy given to me by a skater the other day.
Go to a skatepark with a wallride, you'll see few tire/wheel marks.
Go to a perfect 5 stair wall, you'll see tire marks everywhere.
It's not cool unless you're not meant to be doing it.