My number 1 reason I don't think they should go mainstream:
It'll be the same ol' game of paintball (snapshooting, accuracy by volume, etc) over a longer distance.
As for the environment: The paint and gelatin from regular balls doesn't exactly work wonders on trees either. I suspect that the residue left on surfaces by regular paintballs (i.e. on stop signs) is the same as left by FS rounds, there's just more of it (to up the density).