In current GW3 MAXes are only marginally costlier than NGs. As they have more range & drink less fuel, I don't see the point of still buying NGs(maybe the -600 for niche routes for the player without smaller craft, but that's marginal). Of course, the bug is probably annoying for other fleet types with many following types(I'm thinking about the fokker70-100-120 group, though I never toyed with them). Usually, F100s still have their niche, even after the 120 arrives
And I know by experience what it means to face a huge change in the code for a tiny result, and having people shouting "how come it's not done yet?". It's not fun. Industrial designer are taught to design their products for the ease of manufacture, but not software specifiers.