I don't think that you can change how a WebGL vendor goes about the business of implementing WebGL. The solutions they'll arrive at are a product of resource constraints, organizational structure and planning.
But besides the merits or drawbacks of a particular development approach chosen, jumping a version introduces its own hazard. What if, everybody agreed that WebGL 2.0 was too late, and you'd jump a version? It puts more work before the next update, and what if, by then, OpenGL ES 4.0 is the new hotness? Do you jump a version again? Do you want WebGL to spend forever in development hell and never release another version, or do you want some next version, even if its late and somewhat behind times when it comes out?