The chances of falling from a ladder are small,.. but when you climb those rungs 100 times a day, 250 odd days a year, it isn't long before even the safest & best trained operator can simply run out of luck.
Ladders will never be banned, but they are already restricted, and those restrictions do directly affect window cleaners. I think its only sensible for even the most hardcore trad cleaners to have a basic WFP backpack setup as part of their gear, even if its only used for those really high or awkward windows. I'm not saying everyone should switch to WFP, just be sensible & well informed about ALL the tools & methods of the trade,.. maximise your potential and minimise risks.