Some people can do things and get away with it. Comics are famously like that. Why is it that some guys can say the most horrible things and it's not offensive, it's funny?
Street art is designed to be seen out of the corner of your eye, on the hoof. Art that's made for galleries is made to be looked at in a more static way for a longer period of time and may not be so striking immediately, but perhaps resonates for a longer period.