While pitchers are obviously at danger, it could be argued that the players are more prepared physically and mentally to be getting out of the way or using something thet coaches don't have, the glove, to try and snag it or block it. Of course, the argument that pitchers are in better shape goes out the window with certain physical specimens, but by and large pitchers are better suited to move out of the way due to their age. And the key thing here is this ultimately changes nothing to the game itself in terms of play. Trying something similar with pitchers would entail much more change than coaches wearing helmets, so arguing the whole "slippery slope" angle doesn't necessarily work since doing similar things for players is a pretty huge jump. Besides, safety for umps and catchers has evolved over the years...isn't this along those lines? Hell, umps used to have no protection at all.