I don't think this is as simple as that (and it's not entirely the display's fault). 120hz iidx is a big upgrade over the previous lcds but I'm not sure it is over the games that ran on custom hardware that wasn't just a Windows PC.

I've got a firebeat at home that I play Pop'n on and it feels magical to play with absolutely minimal difference between when the audio and visuals are to where they game expects you to hit notes. Same cabinet but with a windows PC plugged in for modern games feels worse thanks to all the extra latency you get going through Windows (it's especially bad with the audio).

I know modern iidx and sdvx use newer audio apis that are lower latency but it's still more delay than the pre-PC systems imo.