I mean the whole point of the ST was "rock bottom price" and a lot of the things you're talking about would have raised the BOM significantly, or delayed its introduction by precious few weeks or months.

Beating the Amiga to market, and beating it on price were super important.

But I do think there was a serious problem with follow through. The Blitter and GDOS and then the STe came too long to come after. The Blitter never became standard, and the games and software suffered for it. And updates on the operating system were slow and thin until it was way too late.

I do agree that the cartridge port thing -- it being limited to 128kB expansion -- was needless. One more pin, even, would at least allow for a proper OS upgrade via cartridge port! Definitely one of the stupidest design decisions on the machine.