They would be a good option for guys with brittle hands. Much less likely to break your hand throwing palm strikes. They're also good to use in those odd, in between, striking ranges because it can give you a couple of more inches to extend into the strike.No doubt they'll do damage, I just wonder about the concussive force where you're not getting the weight of the fist in there with it.
Maybe it's just my boxing bias, but I just wonder in what situation you'd use a palm strike instead of a punch. I know Bas did great work with them in Pancrase but that was out of necessity. I don't remember him throwing many (if at all) in his UFC fights. I know he knocked out TK with a great punch combination.
I wouldn't recommend completely replacing a closed fist punch with a palm strike but they would make for a nice little addition to add to the tool box along with forearms and proper elbow strikes.