Two counterpoints.
A. It's not that big a mess. If you exploded a real human body in a similar fashion, you would be left with a much bigger pile of viscera and meat. Yeah, if you're right around the target you'll get some blood on your shoe, but no Dominator shot leaves a blood puddle that can't be fixed with a minute of mopping.
B. The Dominator fires a beam of energy. It's actually insanely impressive that it never causes collateral damage, IMO. Most laser guns in media will punch through a target and go out their back. The Dominator eliminates it's target, and nothing else. Compared to the kinda carnage a WH40k Lasgun can cause, it's actually a very "clean" weapon.