Perhaps what's more upsetting than TP runs is the so called "ghost flights" airlines have run in order to retain landing slots.
I must admit I do find it bizarre to read the threads with stories of people doing a trip back and forth and the resulting amusing interactions with the staff as they see the same passenger boarding the plane. When I first read flyertalk it took me a while to adjust to the idea that people were getting on planes purely to earn tier points! It certainly can become a strange obsession that only a few could understand.
If WE think it's odd, imagine how some of the cabin crew must feel!
I do agree that if it's just that one flight you need to get status and you fly a lot of Y short haul like Gaz (and myself), it's very handy to get the status!
Wouldn't it be nice if they let you pay the difference without actually having to fly the flight.