m-j, the UK AIP under "position reports" states that only callsign and FL should be passed on first contact. However it then goes on to say that position and time should be passed in every subsequent transmission so I think I need to keep reading some more
From practice having the position report added helps us controllers with several entry points so we know where to look to find the ident and also the strip in our archeaic displays.
As to the original question, I agree with Charlie Fox.