I was initially in the 'why would you want one camp' and to be brutally honest it isn't truly necessary. Having said that, though, I LOVE my M&Ps with the thumb safety. I have an M&P9 Pro without and it is my only one. I have my M&P45 full-size and my M&P9c both with thumb safety and if everything goes as well as planned I'll be picked up an M&P45 FDE full-size with thumb safety tomorrow to make it 3 out of 4.

I like it as much aesthetically as I do functionally; and I use it as much as a thumb rest as anything!