Fan service only really works if it's a natural part of the story. Sometimes something can show boobs while staying serious. Anyone ever seen devil hunter yohko? It knew when to do fan service and when to keep things serious, and could even do fan service while keeping it serious (have you seen her transform?). So it really only comes down to if it's used to distract from flaws, the same way some games use pretty graphics and bloom (Halo 2 and 3), others use their franchise title (Halo 2 and 3, GTA IV , Bioshock 2, COD modern warfare 2, star wars games), and some use life simulation elements (Fable 2). Besides, if I want animated boobs, I go for hentai artists.