I think they're fine. It gives groups another thing to think about when developing and revising strategies for dealing certain mechanics and fights.
They actually improved that in a big way in 4.5 by cutting the damage loss on missed positionals from 40 to 20. It's still probably hurt the hardest of the melee by extended phases where you can't hit positionals/duties where you can only target enemies faces, but it's not quite as bad as it used to be.