Most game makers are targeting consoles, which just went through a longer than usual shelf life. With the new ones coming online, we will see more PC upgrades from gamers.
Just to clarify, high end for last two ratios are 2560x1600 and 2560x1440. Both were available at least two years ago when I built my current machine, although after some quick research the 16:9 format had some available as early as 2007.
My laptop bias is showing. Those were the highest resolutions available on laptops. They were also the highest commonly-available resolutions for desktop screens, though none of those was the highest that existed.
