Generally the type of people who make graffiti worth looking at aren’t the sort of people who want to draw with a tablet and stylus.

I mean, the people making them, for one.

Never put your phone in your back pocket. I briefly worked at a Verizon store and like 20-30% of broken phones I saw came from people who sat on it in their back pocket.

Until you can use things like banking apps on them they will never be mainstream sadly.