I’m not really an expert on road riding, but I think they may well be adopted by the pros as the system of choice for days when they are racing in heavy rain.
They make all kind of other race/stage specific equipment considerations, so why not use discs in the wet? Never mind the extra power, the advantages are more consistent feel (e.g. not having such a sharp change in braking force when the water on the rim suddenly clears and then your brakes go from f-all to stopping hard) and better modulation (even more important when the grip on the ground is limited).
I’d have them on my road bike, for sure. For the above advantages and for wear+tear. Right now my rims are pretty worn and I’m trying to decide when to pay out for replacing them. Or go ride fast descents with that voice in the back of my head telling me that the wheel might explode. Plus, there are local road that I avoid in the wet because the descents are on steep twisty lanes that finish off rim brake pads in one ride. With discs, I could ride some of those more often.