1. Wear and tear. As long as you don't need to pay the mx bills personally, I wouldn't care. It's like brakes/reverse policies. You do what they want - as long as it's safe. I don't see any safety issues with WXR on from takeoff to landing...
2. With all the radiation that you are exposed to with high altitude flying, weather radar would be the least of my concern. Think RA sensors, other aircraft radars, military radars, sitting on top of 100+ computers in avionics bay, etc.
3. Plenty of people have flown into CBs with weather radar OFF or picture not clearly visible. It's well recognized risk from Airbus. On the topic, why is it possible to almost completely dim WXR returns on ND, and barely able to dim TERR display?