It's probably a combination of supply chain, timing, and design decisions. Supply chain in that the DIS/Lexicon system is integrated and made by Harman/Becker, and perhaps there was a multi-year or minimum order commitment to offset the development costs and relatively low volume. The fact they used the exact same Lexicon system when they switched to touchscreen on the other models seems to support that.
Timing in that the internally-developed touchscreen systems were relatively new (especially given the early Genesis launch in Korea) such that maybe they weren't deemed ready or sophisticated enough for the flagship. Or perhaps the Microsoft-Hyundai/Kia system was going to be the successor (the Kia variant is rolling out this year). Who knows, maybe they'll put a new system in the Equus, provided that it's not really a contract or cost issue.
Design decisions: If they were emulating the high-end luxury cars at the time this was designed, then joystick/knob, aka i-Drive, controllers were the norm. Auto touchscreens are smaller, lower-resolution, prone to fingerprints and wear damage, and have predominately been resistive, not capacitive in design (meaning you have to press down on the plastic screen surface, versus say the newest touch screens that are made of glass and barely need a surface touch).
I don't know who actually wrote the software for the DIS/Lexicon, but Mapnsoft is apparently doing the map updates. M&S is not a third-party company. They're a Hyundai company (
http://www.mnsoft.co.kr). They also make most of the GPS software in the Korean market (60% market share) from what I understand. So take that as you will. They're the ones providing the touchscreen GPS units and they're the same ones that are providing the late map updates for the Tech package.
