Several reasons, I guess. OpenGL ES 2.0 (which WebGL 1.x is based on) is a subset of OpenGL 2.x, without a lot of legacy stuff that made sense in 1997 but not s

Several reasons, I guess. OpenGL ES 2.0 (which WebGL 1.x is based on) is a subset of OpenGL 2.x, without a lot of legacy stuff that made sense in 1997 but not so much in 2012. In a way, using GLES2.0 is much nicer and more streamlined than "desktop GL 2.x". Also, until very recently GLES2.0 had a "conformance tests" suite to check implementations for conformance, whereas desktop GL did not. Desktop GL only got the conformance suite about right now (siggraph 2013), starting with OpenGL 4.4.