People have been begging for this for over a decade now. It doesn't take much to see demand if you look at the Hackintosh community or the eBay market for old Mac Pros.

They've been purposefully avoiding the mini-tower market for decades. For whatever reason (prestige, cannibalizing other product lines, etc) they're not interested.

I know, and I get it. Maybe "mini-tower" is the wrong description. It should be a maxi-cube. I'm not holding my breath for it though, the things they sell huge numbers of aren't terribly configurable or expandable and it gives them an edge that way.