I think the main reason you have people that complain about screens is this:
Many times when the Steelers run a screen play, the down is 3rd and very long.
You see them throw a nice screen play for 10 yards on 3rd and 17 and you think man, why did they run a screen? I personally love the screen play, just for the fact that it gets our RB's out in the open field and able to do some things that they normally can't on a handoff. It is however a letdown when it is run on a 3rd and long play and doesn't get the job done. You have to think of the screen in different lights. It not only makes the defense think about catching FWP out on the edges, but also slows their rush up, and spreads their defense out.
If I have any beef with the Steelers and the Screen play it would be to run it on downs where it may be least expected (short yardage early downs maybe), but I'm not gonna complain when we have started out the year the way we have. I'm sure we'll see some big screen plays to Willie, and Najeh before this year is over.