WebGL is useful for more than just games. For example, I'm using a fragment shader to implement client-side demosaicing[0] in the web interface for my Kinect-enabled home automation hardware (link in my profile if you're curious). CSS Shaders/custom filters might serve as a partial substitute for WebGL, but IE doesn't support those either.
On the bright side, I've seen rumors that IE11 will support WebGL, but that is of little use to people stuck on XP, Vista, or W7 due to compatibility requirements of other legacy apps. As you say, IE doesn't have the dominance it once did, but for some reason it's still used in certain market segments.
[0] https://en.wikipedia.org/wiki/Demosaicing