It is a damned shame, really.

TOS/GEM was so very basic that enterprising 3rd party developers were able to extend it from a single-tasking OS to a complete multitasking one, over time, without totally losing compatibility.

(Yes, yes, before any Amiga owners "Well actually..." me: we know, AmigaOS had that built in... But with interprocess communications designed for a single flat shared memory space, that meant that it could't be extended to support 68030+ memory management without breaking compatibility.)

The ST had the potential to really grow as a platform, just as Atari gave up on it. The TT 030, Falcon and ATW (AKA Abaq) were amazing machines with great potential, but it went unrealised.

Oddly enough, the relatively humble Sinclair QL, which was by Sinclair standards a flop, went on to inspire both hardware compatibles (ICL One Per Desk, Merlin Tonto, Telecom Australia ComputerPhone), motherboard upgrades (Gold Card, Aurora), and up-specced clones (CST Thor, Thor II, Thor XVI), and subsequent compatible machines (Q40, Q60, Q68), and hardware boards for other PCs (QXL card), and its OS continued on other hardware (SMSQ/E).

An impressive legacy for a "flop".