The main issue is that the OS did not have a way to request "chip RAM", thus software compatibility hell if added too late (never actually got added AIUI).
Not that it mattered by that point but TOS 3 for the TT did? For what, I don't know, really. Maybe people running Calamus or something could use it?
I think Atari Corp had a burst of engineering competence at the end after Tramiel Sr handed over the reigns to his sons. But it was too late, the market moved on.
The Falcon is a lovely machine. The last TOS releases addressed some longstanding problems. Hiring Eric Smith to work on TOS/MuliTOS was a good, but late effort. Porting SystemV and trying to make a budget Unix workstation was a doomed but clever effort (I still remember the UnixWorld news clip box headline "Up from toyland").
I bought a 486 late 1992, put Linux 0.97 on it, and moved on.
There were OS support when fastram arrived (obviously). Since their chipset supported 4 megs of chipram (14 megs on later machines), they didn’t have to worry about slowram etc. So it wasn’t really an issue for them.
I'd add that honestly people weren't really complaining about the ST's speed at the time it was current. It beat the Mac and PC for horsepower and price.
While it was kind of a crappy games machine compared to the Amiga, it certainly was better than a PC or a Mac, and as an all around general home productivity computer was the best value for the $ out there at the time. Which I think was the Tramiel's aim.
The main issue is that the OS did not have a way to request "chip RAM", thus software compatibility hell if added too late (never actually got added AIUI).