No. No. No. No.
I'm really not for the whole sex appeal thing in horror movies. Though I'll say that they usually fall under the 'slasher' catagory (which is a barren wasteland under a massive pair of tits and knives). But when a horror movie needs to advertise using the leading lady's body (Under exception: Here. [http://en.wikipedia.org/wiki/Teeth_(film)]), you should put your warning lights on. Sure B-Movies use it a lot, but they're B-Movies, it's their jobs to be about TnA and sex, drugs and rock and roll because that's what we want to see. Oh and shitty rubber monsters.
But TL;DR, No, a horror movie shouldn't be reliant on sex to get viewers. Slashers can because it's kinda their thing though...
