Riddle me this, if USB was so simple to pick up, why did it take five years to have serial adapters & drivers that didn't crash the computer?
I never had an issue with serial adapters crashing the system. But even if it happens, I don't understand how poor coding and testing is relevant here.
I'm not sure if those are rose tinted glasses, but I had very different experiences, usually resorting to BlackBox PCI serial cards, or PCMCIA cards for laptops if I wanted reliability. Back in those days, I worked on and developed autonomous and remotely managed satellite groundstation solutions: dishes, radomes, rotators etc. used across the world at latitudes of -90 to +78 degrees. It simply wasn't possible to rely on USB solutions for these due to their unreliability. It was pot luck which COM port would be assigned to which adapter at boot time, an untenable solution for remote systems.
It's relevant because, in my view, it demonstrates that USB was over-engineered for the time. Some might say it was ahead of its time. At that time the only practical way to engineer a USB solution was to create a custom ASIC, so it was an expensive proposition. That's unlike today where not only are there many solutions, the firmware stacks are mostly fairly stable. Almost no-one builds their own USB stack nowadays, they either buy IP or use a vendor library, and that's for a very good reason: USB is just so darned complicated.
Bluetooth had a similar problem, but it was rather worse, because it confused customers, as not all Bluetooth devices were compatible with all Bluetooth hosts, and the terminology like "pairing" was not standardised between OEMs.
FWIW I have similar views about USB-C, where there remains much consumer confusion even down to very basic things like identical looking cables that aren't functionally equivalent for the plethora of potentially concurrent demands on the single physical interface (USB HS or FS, Thunderbolt, Power Delivery, Diplayport etc), not to mention the physical and electrical fragility of connectors, multiplexers and power delivery silicon.