I suspect they desperately want to avoid further scandal, especially with electric cars because these are supposed to be turning over a new leaf after dieselgat

I suspect they desperately want to avoid further scandal, especially with electric cars because these are supposed to be turning over a new leaf after dieselgate. They're not sure exactly how well battery thermal management will work, so they choose a strict limit. I suppose if they find there isn't a problem they could relax it OTA. No-one complains if they get more later, only if they get less.