I expect pricing would be very important. From what little I've seen of street artists' methods, they probably would like these as an alternative to the plastic caps, but it could all swing on whether they were affordable enough to buy a bunch of them at once instead of just one or two. Spray can artists use spray cans because they enable super-fast K.I.S.S. workflow (comes from the "get in, get out" nature of their graffiti roots), so I think if they like them, then they'd want to have a separate ones for individual cans so they never have to change tips in the field. If they can only afford one or two, then swapping it/them around between cans could negate the efficiency gains, and possibly even result in a net loss compared to the plastic graffiti caps.