I also have a Geforce GT 620, but that's the other way around. When I first tried to get open source working, I had no dispaly on my screen. Without openssh, I couldn't get my computer working again. But install the Nvidia proprietary drivers and everything works fine, including playing WoW through WINE.
As a gamer, the open source drivers offer more in the long term then proprietary drivers do. Especially since my hardware has gone legacy so quickly, if that makes sense. The DX9 state tracker does offer a lot of benefits to the Linux community.
#1 More people will switch over to linux if there aren't performance issues with their games. The gaming community isn't happy about Windows 8, and Windows 8.1 has done nothing to fix it.
#2 The more people that switch to linux, then developers will take notice and will work exclusively on OpenGL. OpenGL isn't going anyway, cause right now it's an OpenGL world. Mac, Linux, Android, and iOS. What reason do developers have to continue to use Directx? With PS4 claimed as the winner over Xbox One, Directx won't have much of a hold in the future.
#3 Lets not forget about the Valve Steam box that'll run Linux. Valve will most likely make all their games in the future with OpenGL. If Valve has any influence over developers, then others may also go OpenGL. But there's going to be some that won't, due to lazy or being influenced by Microsoft to stick with Directx. That's where the state tracker and Wine comes in.