Well, USB-2-Serial became much simpler when FTDI issued their first FT232's. All we had to do was connect a serial EEPROM to host our VID/PID. Brings back memories of FTDI's minuscule stall at Electronica(?), staffed with actual Scottish technical expertise (Andrew?, Steward?).
What do you again mean by "USB 2". FTDI's first chips were compatible with USB 1.1 only AFAIR.
And yes, that made adding USB to a device much easier. They had also released a parallel FIFO version at about the same time (FT245), which allowed nearly the full bandwidth in USB FS, about 1 MBytes/s.
You could do the same with Cypress EZ-USB MCUs at the time which were pretty much the only other "simple" solution available, although it was more involved and didn't come with usable drivers.
FTDI's first USB 2.0 HS (high speed) came much later, around 2007 IIRC. Of course to get the benefit of HS you would need to use a parallel FIFO mode. Even on their latest chips, the UART <-> USB function tops at 3 Mbits/s, for which the bandwidth of FS is enough.
And then they released USB 3.0 SS chips (FT6xx). At this point, alternatives (such as Cypress FX3) are much more expensive actually. I think there are some chinese interface chips supporting USB SS, but I don't have references in mind.
I don't know if they'll ever release chips allowing the new speeds of USB 4. That's freaking fast.