This was sort of inspired by/recreated from a TV.com message board that I found.
http://www.tv.com/shows/arthur/forums/least-favorite-arthur-episodes-2099-3311559/
LOL, I forgot about that forum! I even participated in that thread too.
Anyway, yeah, D.W. did get off light in "Arthur's Big Hit." That whole episode was a mess, IMO (how it came from Joe Fallon is beyond me... I mentioned that in the TV.com forum as well). It would have been alright if it just focused on Arthur and D.W. dealing with what happened, but for whatever reason it had to go off on a tangent and become an episode about Binky dealing with peer pressure from the Tough Customers.