What makes sense: a) Nvidia is looking into supporting Optimus because Linus showed them the middle finger, or b) Nvidia is looking into supporting Optimus because the graphics stack is now capable of it thanks to dma-buf and xrandr1.4?
Switching from twinview to xrandr1.2 is different, it means existing DE tools for monitor configuration now work. Also, twinview didn't support rotating a single display in a multi-monitor scenario, whereas xrandr1.2 does. There might be a few other benefits that I can't recall currently. There are no such benefits in switching kernel modesetting implementations.
Though sometimes we do get goodies that appear desktop-only (VDPAU), desktop Linux is nevertheless low priority for Nvidia. Because the market share simply isn't there.