That seems like a great shift. Higher quality with the same (if not greater) level of exposure. What's the downside? Streets stay cleaner too, and less people get in trouble for a "harmless" crime.
The article also compares Banksy to Selena, I'm familiar with Banksy, but who is Selena?
I wonder if the next transition is to move away from physical graffiti entirely to digital graffiti (imagine a Wii remote style paint can directed at a tablet) -- as hardware prices fall this could be increasingly affordable, even for those with lower income, and definitely more affordable than getting in trouble with the law.