" First if it is so damaging why does the fishing here in Missouri just keep getting better?"
I don't believe it does in some areas, for many reasons.
I think much of the problem is an old tendency by some to gig what they want, equipment that takes gigging to new levels, little to no enforcement, and maybe the one key item that binds it all together, low water levels.
My first choice of action would be some serious enforcement, combined with some changes or additions in the law. A change in the Smallmouth limits to increase numbers, closing the season on Smallies during the gigging season would help some, and a limit on lighting to limit the range of illumination. I'm sure there are other things that can limit conflict and I've never advocated banning gigging, but as an old native, I've heard my share of stories.