The most profitable game market is the "casual gamers" market...
And most of these "casual games" have required a DX compliant video card for the past seven years. My minimum test machine is a P2 500MHz, 128MB RAM, Geforce 2 MX 400 ($20 card), running XP. BMax flies even on something as ancient as this. That is the minimum I shoot for and this is a VERY old system.
I allow people to adjust the refresh rate for the game, and for people with POS cards, they can enable delta timing that will make the game look good even on Trident & Savage mobo chips.
A 3D card that is DX or OpenGL compliant IS a minimum requirement for BMax.