And you did not say which areas and why it is behind in them. I see multicore support in another comment, and maybe things related to geometry shaders. What else am I missing?
Geometry shaders are in OpenGL 3.2. Almost any complaints about "OpenGL is missing X feature" ignore the existence of the entire 4.0 generation as well.
Which is kind of understandable - I use Mesa as my "assumed" OGL level, and it just hit 3.3. So you absolutely can't assume anything from the 4 line.
Though I still couldn't use geometry shaders as an assumption, because as recently as Sandy Bridge Intel GPUs didn't support it. Add on if you want to port to mobile you need to refactor to GLES2.
