Pitbulls can be good family dogs with the understanding of certain physical realities.
Pitbulls are very powerful animals ( many years of working with them and torn knee cartilage attests to this ) and we do not know the admixture into the gene pool of artificially selected fighting dogs. Pitbulls have a fairly strong bite force ( not as strong as Rottweilers ) but they tend to hold on and rend in their fighting style. They may attack small dogs so they need strict socialization. The Pitbull dog is not for everyone and needs good training, on average, though you will find some Pits quite good right out of the liter.
That many Pits are used as extensions of someones limited masculinity is a great part of the problem. Dogs trained to be fierce are one thing but train a Pitbull to be that way and you have problems.