Cheesy as it sounds, effects updates probably have a lot to do with it, too, given the gory and/or fantastic imagery horror or fantasy/sci fi films often deal with. I mean, let's face it: it's got a lot going for it in other areas, but the effects are what initially drew a lot of us (and a lot of other film/horror nerds) into the remake of "The Thing". As well they should, in that instance, since they were brilliantly conceived & executed & helped the filmmakers realize their (and John Campbell's too, I'd wager) vision of what the Thing was, and why that was scary. Similarly, the effects in the remake of "The Fly" allowed for the presentation of the transformation as akin to a slow, progressive degenerative disease in a very horrific & believable manner. In cases like that, the effects enhance rather than mask the film's other qualities, including those of a well done remake. Of course, effects alone don't guarantee you a good remake; a case in point: the Matthew Broderick version of Godzilla. Cool effects, you gotta grant. But a film so weak in every other area, it fails & won't make anyone's "best remakes" list.
EIDTED TO ADD: This was in response to Greg's post about the updating of films by filmmakers w/ their fingers on the pulse of what scres modern audiences. Screwed up the quote thingy.
