In a perfect world, there would be little or no need for weapons. If all humans were benevolent we would not need to concern ourselves over self-defense.
Using a weapon involves the threat of death or harm, or actual death or harm. I wouldn't call that a pure good, even if the purpose for using the weapon IS a pure good (protect my family from harm by an aggressor).
But the world isn't perfect and never will be, nor will all humans ever be benevolent.
Very very few things are mitzvah, pure good. Automobiles are not pure good; industry is not pure good; heck even food is not always pure good is it?
Guns are not a pure good; however I see them as being strongly more of a good than a negative for a variety of obvious reasons.
My Constitutionalist side tends to resent any infringements at all on the 2A.... however my pragmatic side recognizes that our society does a lot of things that are Constitutionally questionable and that sometimes compromise is better than the alternative. Therefore I grudgingly accept certain small infringements, like the National Instant Check System and CCW permits, as a compromise I can live with for the sake of the desire to make it harder for criminals to get guns, even if I doubt its actual effectiveness.
I would not object to adding a red flag to NICs for those who have been involuntarily committed, for another example.
In general though I think we have plenty of gun control laws already and don't need any more, and it would take considerable factual evidence of some new laws benefits to persuade me otherwise.
Rights are not rights unless they are jealously guarded.