Mine is about the third M&P I bought hoping to like the thumb safety, and I agree it needs to be just a little bit lower. My current plan is to take it out (when both plugs are back in stock at Speed Shooters Supply) and go without while I experiment with fabricating something to create a lower paddle. If I ruin it I will have a pistol without the safety, if it works I will win the internet. Or at least the Pistol Forum part of the internet. Actually probably just the M&P 2.0 Compact thread...
If you buy AWIB from JMCK with a full guard pretty sure @TonyMayer can form the holster under the paddle. My IWB #3 is like that, but these days you may need to request it.
Creating a safety that was strong side only would be so super simple even a caveman could do it, and a legitimate use of a Dremel tool cut off wheel. You could easily cut the off-side paddle off, and install one frame plug. Hmmm, I was wondering why only one side was out of stock...