jadeite :
The whole reason people want mini-itx is because they want a small case. These cases are huge bloated boxes 13-17 liters in size. You can get micro atx cases well smaller than that. A properly designed mini-itx case is under 10 liters and still accommodates the biggest graphics cards. Reviews and specs need to start publishing the volume in liters of a case because it is a key buying factor. Cases like the Dan A4 do a really good job at compacting a case down to 7 liters for instance.
The only "sizes" that matter are length, width, and height. These things tell you whether a case fits into a specific location. Volume is only a "bragging rights" calculation: Because it doesn't tell you how wide, how deep, or how tall a case is,
volume is meaningless to any real-world situation.
Of course you could say that all of these cases are too wide, or too tall, because you don't think a Mini ITX case should have room for a full-sized graphics card or mid-sized CPU cooler. But then you're scratching off a big portion of the portable gaming market.
And then you could point out that consoles are smaller, in which case you'd be starting the whole console-vs-PC debate rather than a size argument.
Or you could be arguing for the placement of non-high-performance mini PCs, but the thing is that there's scarcely a reason to build a boring mini PC since so many cheap ones are being sold prefabricated. I had my Wife on a Brix until she knocked it off the table one too many times. If I were shopping for a Brix, I wouldn't even be looking at case articles.