It's one of those casting choices that beg only one question: Why didn't someone think of this before? In Willard living waxwork Crispin Glover (''Back to the Future'') takes to the role of rat-loving loser Willard like a rat to rat-nip -- by himself, he's this remake's raison d'etre. The movie's pretty good too. Writer-director Glen Morgan (''The X-Files'') gleefully shuttles Willard between ''healthy'' self-possession (represented by the diplomatic rat Socrates) and vengeful psychosis (Ben, a big critter with even bigger stage presence). EXTRAS If it's a descent into madness you're looking for, try Glover's ''Ben'' music video -- with Glover's commentary on.