The thing is, we need to kill bacterias in many other places than the human body:

- medical equipment: handles for scalpels, syringes, operation tables... All those things we need to clean again and again.

- passage ways: doors, handles, stairs handrails, subway grab bars... All the things that propagate infections in very dense populated areas.

- research fabs: hazmat suits, protection googles, fum hood protections,... All the stuff you want to make sure don't end up cross contaminate your batch or escape.

So it's still very useful.