The basic concept of a lifter is that it increases the leverage you have on the ski as it makes the distance at which the force is being applied further away (Have a lever long enough you can move the world, that sort of thing).
Some people say it helps when carving, and others prefer to be lower as to minimize the effects of being a little off balance on a landing  and potentially having the ski pull out from underneath them. Most likely it makes very little difference, but that doesn't stop people from having vehement opinions on the subject.
Personally, I don't use any lifters, as it is one more thing that can break on the binding, as well as the idea that makes landings less tricky when a little off balance. That said, if there was a deal on a pair of bindings  I really wanted and they had a lifter, or I was getting a touring binding, I wouldn't mind it.
Seems to me that it's importance is vastly overrated, and people spend way too much time talking about it. Kind of like this post.