With Windows users NVIDIA know that they want pretty games and they want them prettier very year, and they also know that Microsoft is probably going to work with them to make that happen. They've also got game developers and hardware vendors lining up to get NVIDIA logos on their products.
Whereas in Linuxland, they've got a kernel, a billion side-projects that may or may not be widely used and they all want NVIDIA to conform the THEIR way of doing things, an angry Finnish gentleman who just shouts and swears at things he doesn't like, and a largely non-gaming and very fragmented user base that could be using any number of desktop environments/kernel versions/drivers etc. On top of all that, this menagerie only accounts for about 3.8% of the desktop market. And they're also kicking and screaming that NVIDIA isn't doing enough to support the things that they want to do.
Sure NVIDIA could be working faster to better support Linux by throwing more people and money at it, but they don't have to and until more people use Linux they don't really have much of an incentive to do so. They'll probably have better Linux support, eventually, and if that fits in with their business plan then that's fine. If you're a Linux user and NVIDIA doesn't do what you want it to do, then that's fine as well - vote with your wallet and buy from someone else.