I think its just that the haters are louder and more obnoxious, and therefore they tend to drown out the calm, reasonable voices of the lovers. That's why people have deluded themselves into thinking KOTCS is considered an all-round awful film, when it really is nothing of the sort, and most critics agree.
And let's not forget that when it first came out, reviews were quite warm. But once the fan backlash started, critics, in a desperate attempt to regain credibility with the fanboys, went back on what they said and began to bash it as well. Aint it Cool News is a particular example of that.
Yeah, it's quite tragic how some can bring themselves to hate a Jones adventure, as the Indy films really do represent the epitome of the medium's possibilities for making simple, fun, jolly good entertainment.