I think it's strange to do graffiti that automatically and by pure nature of its existence looks easy. It looks easy when I pick my nose. It looks easy when I run out of toilet paper.
BUT.
These guys tell us something very interesting. There is an actual challenge, a certain je ne sais quoi to their work that is actually, in a hidden sense, very difficult to master.
It reminds me of my friend telling me last night about a Jiu Jitsu magazine in Brazil that had Down Syndrome people on the cover, in fight stance.