Bats DO help with the environment...
The foods that bats eat make bats crucial to the preservation of most of the Earth's ecosystems. Insect-eating bats typically consume about half their own weight in insects during a night's hunting. Without this occurring, the insect population could explode, threatening crops and the balance of nature. Bats that eat fruit disperse small seeds in their droppings, sometimes scattering them in locations far from the parent plant. Because many fruit-eating bats live in tropical areas, they play a vital role in maintaining such habitats as rain forests. Bats that eat nectar and/or pollen, carry pollen from flower to flower, helping to pollinate plants. Pollination makes it possible for the plant to produce fertile seeds that grow into new plants.
They hardly ever carry rabies either. Only 2 cases, in 1966 and 2002 were bats found to carry the EBLV 2 virus. Rabies-carrying bats are usually found abroad, have little contact with people and don't nest in houses.