I have never watched "Will and Grace" but it is my understanding that the show never shows Will actually kissing another man. Men can be quite turned on by an Elizabeth Berkeley - Gina Gershon tongue session but will be revulsed by the sight of two men at each others rumps.
That sounds right to me. I find it amusing that some libs who (properly) say those on the right can't denounce films they haven't seen are already saying this movie is a classic and if you don't like it you're a homophobe, without having seen it themselves.