I've been happy to stay with rim brakes for the conditions here. The limit on stopping power has always been due to the tires and bike geometry (i.e. avoid flipping) rather than the brakes. I have occasionally had to replace front rims due to brake wear, but it's been at over 50 kmiles of use so hasn't been too much of a concern. But we have a rather limited rainy season - those with more rain riding would see more rim wear.
So I haven't seen a reason to go with the slightly heavier, more expensive, and more complex disk brakes - YMMV.