Read the previous posts in the thread, please. The first model Megadrive/Genesis is widely recognized to have superior sound hardware to most of the subsequent revisions, but for whatever reason the model 2 console is more common.
Asking why someone implements a game machine mod is like asking why someone climbs a mountain. Most of the time, we do it strictly for the sense of achievement. Certainly, the well-tested and well-researched OEM hardware is good enough for most applications, but at GamesX we're hardly representative of the gaming public at large. We like SPDIF, we like channel-separated waveforms, and we like standardized connectors. When asked why, I counter 'why not?'