Well they will sell fewer units per model so you will have fewer of the model you want to look at on the lot. You will have smaller quantity of scale discounts. Each spin-off model has colors, trims, options, its madness. Just my opinion but i think they should just hammer down on the CX-5. Discount it, sell a ton, forget wasting time on so many slight size variants. Not sure why you need a CX-3 and CX-30 its so close together.
It's all SUV's these days, I think the CX30, CX5 CX9 and 2019+ Mazda3 all share large amounts of chassis bits, the CX3 was based off the Mazda2. The CX30 should be much more of a drivers vehicle. The market is SUV's and upscale trucks in any size and engine and transmission configuration you can think of, sedans area dying breed, unfortunately. I was briefly considering a CPO CX5 or CX9 or even a 2019 AWD Mazda 3 hatch to replace the G37x in the next few months, but then I remembered how much I like driving every time I get in a sport sedan and the number of deer and elk and other road hazards I've not hit because of it that an SUV would have plowed into. Enter one can have a one owner no accident 40-60k mile 13-15 Lexus GS350 AWD for under $20k and just budget $3-4k for repairs over the first 3-5 years.
I get the impression that the CX3 is on its way out in the US. The CX30 is the successor. Also the Mazda 3 will have a awd option if one doesn't want a crossover.
There is also the CX-X coming soon. That will be assembled in the new Alabama plant. Bigger than the CX5 but not as big as the CX9.
It's a transition of model choices imo.