So much for the public's hunger for anything in 3D. DreamWorks Animation's "Shrek Forever After" bowed even more lightly than some had feared, with the family comedy topping domestic rankings with just $71.3 million in estimated weekend boxoffice. The latest Paramount-distributed pic about a lovable ogre and his family debuted with significantly less green stuff than the two previous "Shrek" sequels, which each fetched $100 million-plus in their first three days.