I golfed with a 13-year old kid last week who was deadly with one of those chippers. He had three 0-putts on a nine hole course because of it.
That said, to me, the easiest shot in the world is a chip shot. My pitches aren't nearly as good. I find that using a chipper not only seriously reduces one's options when playing from just off the green, but it also puts a club in my bag that duplicates what can be accomplished without it. With a chipper, you get one kind of shot. You get one kind of loft angle, and you are limited with what you can do. When I use my irons, I can shoot my 3 iron from the fringe instead of my putter. The thicker the grass is, and the more grass I have to shoot over, the higher I can go with my club. If I end up with too much grass and not enough green, I'll shoot a pitch shot instead.
I don't like to hear people compare chippers to hybrids. A chipper has one purpose. It's extremely limited in what it can do, and what it can do is duplicated by several other clubs in the bag. A hybrid, on the other hand, has several different purposes. I can shoot it from the fairway, from the deep rough, from the tee...I can even chip with it. My 4-hybrid replaced my 4-iron because it can do what I did with my 4-iron and more. With a chipper...any of the clubs I'd contemplate taking out of my bag to put a chipper in instead, I can alread do with that club what the chipper is for. And since chipping is the best shot I have in my arsenal already, I just don't see a purpose for a chipper.
That said, mjaber is right. Chippers are legal, but they have some prettys strict restrictions.