Actually, in many cases Android does use the software renderer.

Take a look at /system/lib/egl/egl.cfg In many cases where I've looked (though it varies on device) the software renderer does get picked up. If you remove the entry for the software renderer, it often speeds up in general, because hardware is forced to be used.

It practice it doesn't very often unless there's a very weird EGL configuration being requested which the h/w version doesn't support. But your point applies that you'd be better off removing the s/w renderer.