Hi-HooYah!
You have hit upon something I have always figured. If it's not mainline, folks don't want to mess with it. ATCs and others are always underrepresented. Look at the market for LCMs. Someone comes out with a 3 boat and everyone thinks that's great. The only 6 boat I ever saw was available in VERY limited numbers for R.C.only in 1/96 scale!
Now they are popping stuff out in 1/35. With outrageous prices( To Me) and they're not necessarily what warms my heart. I mean really, How many P.T.109s can we get? This is as bad as Destroyer Models! I remember when Tamiya's or was it Hasegawa? Came out with the PERKASA MTB.Twin colors molded in the hull and moldings so fine, you better be up on your skills.
One final thought. What is the most forgotten scale in Armor or related subjects? 1/32! Remember LINDBERG? That company with the "Crappy" models( I never thought so) They soldiered on with LCI-LCVP-and Coast Guard Cutters for years. Good bases for great models. They also continued on with many others for years." Bobtail Cruiser" and such, Plus the Carronade Ship and the LST. Different scales, yes! But the possibilities. Oh Well!