If you're honestly looking at it from a more generalized, abstract position, then I'd answer that we don't -- as citizens -- need guns. However, one of the appealing aspects of liberty is that you are allowed a great deal of choice and freedom in exchange for personal responsibility.
Yes, guns are made to kill. However, a bullet isn't the only way to kill someone. A knife, poison, and even a piece of rope can all be used to kill someone. Liquor is arguably even more dangerous and unnecessary than firearms, yet we all know how the general population would react if there were another attempt at prohibition.
We have a right to own guns because it's one of the freedoms that living in a free, equal society affords us. Yes, living under a government which restricts ownership of anything dangerous would be safer, but would it be appealing? Think of what happened after 9/11 -- the Patriot Act (et al) made it much harder to bring items on an airplane which could endanger other passengers. However, the downside was that the cost of airport security went through the roof, security lines got longer and slower, and if you try to bring an open bottle of poland spring water through security you're likely to get tackled by a national guardsman and interrogated by the FBI. Personally, I'd rather have a freer society which runs the risk of people abusing their liberties, than a closed society which can guarantee me a 100 year life expectancy but prevents me from doing anything which might endanger myself or others.
Really, if you feel differently, then I don't think you truly understand and appreciate freedom. We live short lives, and it's so easy to forget (or to never even realize) how unique and special the freedoms we enjoy today are when compared with all the oppressive forms of government in the past. I'm not calling you stupid or anything like that, this isn't a personal dig, I'm just speaking to the collective ease with which a culture can forget how it got where it is, and why.