I get what you mean and I own a lot of iPads i’ve picked up along the years. The mini, the basic 2018 ipad, and a 12.9 iPad pro. I personally like the concept of the current mini but it’s the iPad i use the least. I think they can keep the same footprint and increase the screen size and make it more compelling.
But you’re right choice is good, but it’s still a business and they have to justify a product and have it appeal the most amount of consumers to make it viable. I have no idea what the sales figures for the mini are, but I think a slightly bigger one will appeal to a wider audience.