Many Latin American countries have permanent graffiti, and I’ve seen many that have Wayspots. Most of what I’ve seen has not been commissioned, but aren’t tags, which are ineligible. A good deal are unique paintings (I see a lot of pop culture characters, flowers, cultural references), and help brighten up many areas.
Certain areas even establish places where graffiti artists are welcome to paint; my city has a well-known artist wall in an alley downtown that anyone is welcome to contribute to, including graffiti artists. There’s a plaque marking the wall, and it’s used as the photo for the Wayspot, as that doesn’t change, just the wall art.
Niantic does has criteria clarification on what they call street art, which is similar to graffiti, so it may be helpful to look over that.
I personally do not agree that all existing graffiti Wayspots should be removed, and I can certainly see some being upset if ones that are publicly accessible become ineligible. Graffiti Wayspots do get removed from time to time if they don’t meet criteria, and Wayfarers are certainly welcome to request removal if they believe they are ineligible.