TfL are caving in to the taxi-driver cartel
This is a blatant attempt at protectionism. The driver knows where you want to go because you entered your destination when you booked. If you want to freestyle/change your mind/get emergency medical help then don't book an Uber in the first place.
The arguments made on safety grounds are totally spurious and could apply equally in many other situations that have nothing to do with hiring transport. The fact that the hapless but unharmed Aaron Wray is the best example the Sun could come up with indicates that it's unlikely passenger safety is being compromised.