laws only apply to those who abide by them. so it won't effect the criminals to much except maybe reduce the total available to them if the general public doesn't have em.
having said that. in the past i have enjoy'd going to the range and pulverizing a target or shooting some rabbits (pests) on a mates farm so i don't see the need to ban em. just regulate them. i personally don't have firearms at home but my brother does.
someone mentioned compulsory ownership. there is one province in a american state (texas i think) where this is the law and they have fairly low crime rates if memory serves correctly. i also believe you can't just buy the weapon, you actually need to attend some sort of course where you are tough proper handling techniques/cleaning and storage etc.
here in NZ it's not totally easy to get a firearms license. you need to sit test, the police speak to two persons to get references, they visit you residence and talk to your family and you need to show that you have adequate storage facilities for any firearms that you may purchase (which is dependent on the type of license you get) assuming you get said license.