What is your solution for this scenerio? The defender can only go for the ball? Blame the route then, why design a route where the WR is standing there waiting for the ball and as a result waiting to get drilled by the defender. Blame the coach who drew up the route, blame the QB who throws it to the WR when a defender is about to level the WR. Maybe the solution is to ban dangerous routes that hang the WR out to dry.
I would think that the helmet companies could design a helmet that absorbs way more of the impact that what is on the market now. That would help alot with injuries.