I know one of the reasons the FEI has come up with the new complicated rating system is to discourage riders from moving up just because they can or from starting a horse at a particular level just because they can but am I the only one who suspects it may have the opposite approach, especially with respect to the requalification of the pair question.
I'm afraid the rider qualification will become a goal in and of itself and that the very public nature of the fact that Rider X is so special that they can take new horse Y out at level X without qualifying will lead to sort of a bizarre pressure to do just that.
It reminds me a bit of the whole Kentucky Derby earnings qualifying system. Before the points system, many years did not have full fields. Once they put the earnings system in place, qualifying for the race, being in the top 20, became a goal in and of itself and rarely did a sound horse with enough earnings to get a spot in the gate, not enter the race. Even if they had no chance to win-the publicity surrounding having earned the right to enter the race created a sort of expectation/pressure that the horse would be entered.
Not a perfect analogy, but it will be interesting to see if these ratings create unintended consequences.