1) When the only thing your pointless remake has going for it is a higher budget for gory makeup effects than the original, it is not to your benefit to hide the gory makeup effects by setting everything in such dim lighting that you can't actually make out what you're looking at in the darkness. This tactic also fails to enhance action scenes of people running from homicidal maniacs. Particularly when one of the things that the film you're remaking is specifically renowned for is demonstrating that dark != scary, by setting much of the horrific action in full daylight.
2) At some point, the following conversation should have taken place (spoilers below, if you care for some reason):
SCREENWRITER: You know what would be really cool? Ok, Leatherface takes the Lead Generic Young Person and throws her in the furnace room where he does his nasty stuff, and she finds her friend, Generic Young Person #2, hanging from a meathook, but he's still alive, and they can't get him down, so he begs her to "end it", so she grabs a knife and stabs him to end his suffering. Wouldn't that be awesome?
VOICE OF REASON: But why would Leatherface, who is apparently competent enough that he's been killing people for some time now without getting caught, leave a victim wandering loose in a room where he's got knives lying around? Big knives which could be used against him as weapons?
SCREENWRITER: Well, he is insane, maybe he just forgot. Although, now that you mention it, we don't really want her to be able to fight back... But that's OK, we'll just have her leave the knife buried in the guy's stomach.
V. O. R.: So she's scared out of her wits, but she just abandons the one weapon she might be able to defend herself with, even slightly? Great, so this will be yet another horror movie that depends on its characters behaving like morons. Oh, and by the way, stomach? She ends his suffering by stabbing him in the stomach? All that would actually do is make him hurt worse, and maybe allow him to eventually bleed to death in slightly less time than it would have taken anyway.
SCREENWRITER: You're right, there are too many problems with this idea. Forget it.
V. O. R.: While I'm at it, there are six or eight other scenes I wanted to talk to you about...