BGA
Our Airbus (A-320) FCOM says the following in the Taxi checks
RADAR (if required) - ON
My understanding is if Airbus wanted the Radar to be ON all the time, they would not have written (If Required)
As mentioned earlier, these radars have a lot of moving parts and all of them have a MTBF. So by switching them Off when not needed is prudent.
So keep the radar ON for Takeoff but when settled in the climb/cruise and with unlimited visibility and with not a cloud in sight, it is quite Ok to switch it off
My two cents