Let me just say, as someone that was involved with a startup company working on one of the first commercial MMOs, DOS was a dead-end. No real native multi-tasking/threading, and doing networking at the same time as graphics, and input, was a mess. I was involved in the DOS port of the game, which, was ported to Windows 95, as soon as the "Games SDK" aka DirectX 1.0 came out. The Win95 environment offered so much more freedom as far as programming possibilities, and gaming, it was 100% hands-down better than coding for DOS.
Some of you may pine for the "Good Old Days" of Yore, with DOS bare-to-the-metal gaming, but honestly, it was just a major PITA. The game programmers had to code for every different major brand/type of sound card, joystick, etc., not to mention, Super-VGA card, or the early nascent 3D "accelerators". I don't really miss it. Yes, it was straightforward, but it was also limited. Kind of like a horse and buggy. I like my Power Windows and Power Wipers, among other things, thank you.
Edit: And yes, I've also coded GUIs for DOS.