It probably would be, however Ethernet is far better at handling and recovering from noise problems, as it can handle and resend lost data packets, whereas USB doesn't have that capability. I do suspect USB comms could be improved to handle these situation better, but it'll add cost, complexity, and processing overheads.

I know from various USS discussions, Greg struggled to fit all functionality into the USS, so I suspect it was having to do the bare minimum to handle communication. When it came to the ESS, Greg used a larger FPGA, and I do suspect there may be more going on within it to handle communication problems.

I also suspect other manufacturers have looked at the issues from the USS, and implemented strategies to better handle communication faults, as other good quality USB controllers don't seem to suffer from anywhere near as many communication faults.
You have to remember USS was the first successful USB external motion controller for Mach3, and it did achieve a lot, however I do think it's probably time to retire it, or at least update the hardware.