Yeah, if it's not the Pro or Pro Max, I feel like most case companies don't bother or put in as much effort. Pretty frustrating at times. There's usually enough options overall, but you're often stuck with the "boring" color options/styles. I understand the economics of it to a degree, but as most of us will agree, finding the right case or having multiple options is important and us Air or regular 17 owners are missing out on some cool options.
Edit: I'm surprised the regular 17 is treated similarly to the Air since the regular is supposedly a big seller. But, I think it makes sense if you figure the base model is supposed to be for the "everyday" user and not the enthusiast like the Pro/PM. Research probably shows that Pro/PM owners are more likely to spend more money on cases/accessories.