I don't agree that its gimmicky. You can take some photos that by nature are not possible to properly expose, and get results that you can't even get with your own eye in real life.

For example, you have a landscape with a bright sky but your foreground is in the shade. You expose your shot for the landscape. Your sky will be blown out without a polarizer. Expose for the sky, and your landscape will be underexposed.

Taking this into consideration, you take three shots. One underexposed (-2), one normal (0), and one overexposed (+2). You get on the computer and take the properly exposed sky from the -2 shot, the properly exposed landscape from the +2 shot, and whatever you want in between. You end up with a great, fully exposed picture with next to nothing under or over.