The best art makes you think and/or feel, and engage with it in a personal way.

There's nothing about subtly in that claim, and all forms of art are equally valid, if not the same quality.

Bansky's art has always been blunt and whimsical, probably because he makes popular street art. It's meant to be "accessible" for your average passerby who might only engage with it for a fraction of a second, but maybe get a little surprise when they do.