I agree that cheap guns are a major part of the problem. It's also the one we do not focus on, since the cheapest guns are the ones that are obtained illegally, and we do not seem to be too concerned about illegal gun ownership. We focus on the damage done with legally-obtained guns, but deliberately ignore the huge toll caused by illegal guns. It is the latter that is the reason why so many places that have the strictest gun control also have high numbers of gun-related crimes and deaths.
It is treated primarily as a political issue by the left, since they are determined to end legal gun ownership. The odds of ever achieving that are almost zero, because the USA has a very deeply-ingrained gun culture. The practical approach would be to work on getting rid of illegal weapons, but there's not enough to gain politically from that. So we do a lot of huffing and puffing, but don't ever really make progress on the problem.