Frontier are building to what people use. Most people use combat and generalist ships. The end. Dedicated role ships have historically been compromised to the point of obsolescence and so folks simply use what works; combat ships and multirole.
You are arguing for global variety, which is noble. And I tend to think Q4 may have a couple more ships with long legs? But let's be honest all the "exploration experts" want frontier to take exploration back to walking everywhere with a ball-and-chain attached, ideally if we're blinded and unable to see anything at all, it'll be perfect. But I digress. Most people are looking for variety in combat ships and multirole. I can say that, because Frontier would instead be building endless exploration derivatives if that was the most common activity. For a while, they built ships with a lot of cargo capacity because of trading being a thing. Cutter is pretty much the epitome of that outcome.
People always want to believe their chosen thing is the most popular; they won't all be. That's just how it is, I am afraid. And it's not actually that super different for many developers. They build what people want for the most part.
They can see the player counts, friend, they can see what people are using, where and when. Frontier may not have the finer points down on all mechanics and 'the meta' and struggle a bit due to low play time. But they can see who is using what, when and how often. They're building to the audience. Most of them like shooting, or carrying the kitchen sink. It's why exploration, mining and powerplay are at the bottom of the pile - because most of the loud voices associated are very much against change and the audience size is smaller - that's been true since Alpha.
I agree. But there's no point arguing the numbers, mate. Frontier are just doing what they can at this point; right now that's adding variants to popular ships because that's the path of least resistance.