Seems a couple of posts were silently removed.
But anyway, ipwnz, you say it's not rocket science, but imo your basic premise is flawed. Let me put across an example. If someone posts a 50k fair price item for 45k, that's a great deal. You pay, and then the seller goes silent for a week, then tells you it'll take a week to ship, and then ships in 3 weeks.
According to your logic, the seller gets positive feedback because it was a "great deal". Unless you're using some other definition of deal which makes the seller behaviour a "bad deal", in which case you're arguing semantics and the feedback is indeed for seller behaviour.
How good a deal it is, with respect to price, is visible on the thread, and that variable will change from time to time and sale to sale. Feedback should answer a single question, "Is this person a decent, reliable person to deal with who is truthful and does as they say they will?"