I stated previously that is can get a little messy walking on mulch, particularly as it ages and breaks down. Also, I like to keep "crap" from being incorporated into my mulch, and the fabric prevents that. Lastly, I hose my greenhouses down every so often, since mine are truly working greenhouses. Hosing down the floor with a power nozzle, washing everything out through the open door, removes a lot of debris that would settle into the mulch. Other than that, bare mulch is just fine and dandy.