I have wondered this myself.
I have thought maybe it has to do with the Right to Carry laws that were passed about that time.
I did not check every statute, but a quick check of several under Title 39, Chapter 17, Part 13 Weapons, showsmanywere created by Public Chapter591 in 1989.
I wonder if after Handgun Carry Permits were issued they decided to just completly redo all the weapon laws. And for whatever reason basically make all weapons (even long gungs) illegal outside the home unless you have a HCP or meet other criteria in 39-17-1308