You have obviously never ridden a Norton Commando then
First bike I ever had with disks, used to scare the stuffing out of me in the wet, believe me, you never get used to that split second of nothing when you touch the brake lever.
I'm sure the kind of disks we are talking about are infinitely better.
I have and around the same era early 2 stroke Jap sports bikes which where just as bad if not worse with their stainless disc's. How many modern motorbikes do you see that are not fitted with disc's, Off road, Sports or Tourer? very few I bet. During the 70's I raced a Triumph 500 Daytona that had the front end modified to fit a single disc using lockheed components the discs being cast, rusted at the fist sign of any damp but it did work in the rain. No better than the 4 leading shoe drum that was on it before but did not fade towards the end of a race like the drum did.
Disc's are no stronger at braking than calliper brakes they now just work in many condition mainly down to all the development on MTB's over the years. They also have great modulation which should help prevent locking the front while descending in the rain. If they did not work more predictably in adverse conditions you would not see them on nearly every MTB and increasing amounts of Cyclocross bikes.
I have on a particularly nasty ride from London to Brighton in heavy rain all of the way worn out a set of practically new brake blocks and the rims must have taken a hammering judging by the amount of grey gunge. I am not saying that the disc pads would not have worn but I doubt they would have been anywhere near the end of their life under the same conditions and of course the rims would have been untouched.
I suppose in the end each to their own, me I tend to use the newer technology as and when I feel it is appropriate and in my case with a new build that is intended for a specific purpose in my mind it is justified. Either way I will let you all know how I get on.