A few months ago I got into a discussion with some left leaning friends that wondered the same thing. "Why can't we have a meaningful debate about guns?" It mostly boiled down to things like magazine restrictions, banning 'assault weapons', and limiting where people can carry concealed. I pointed out that these restrictions have failed to really protect anyone and are only feel good BS. They responded by saying that the NRA was mean, blah, blah, blah.
I am oversimplifying the argument, but basically that is what has happened every time I have participated in a "meaningful" discussion. Therefore, when I hear the word "meaningful" in regards to gun control, what I hear is that the other side wants to impose all sorts of restrictions to show hat they are doing something and really is not interested in hearing about logic, individual rights, or reason.