Also many calls beginning with, "XX Centre, XYZ, IFR Taxi".
You have a flight plan in. No need to notify
Isn't it simply done for the purpose of being polite and helpful? I do exactly as the above and have done so for decades simply because I can't see the other person. For all I know they might well be engaged in something other than waiting for me to blurt out my details staccato style. The pre-emptive call lets them know I am reading to give them location, runway, POB and destination.
Of course I could be wrong, any FS folk care to comment.