I don't like quality points. It's hard enough for a casual fan to follow a player's ranking without having to take them into account. Besides, looking at some of the number 1's we have had over the past 12 months, I'm not sure anyone really deserved massive bonuses for beating them. Really, if a girl can beat a top 10 player, then shouldn't that victory and the chance to move into the next round be its own reward? If the girl is really in good form, she'll go beyond the next round and pick the up extra points as a result, and if she can't, then obviously it was just a fluke win in which case I don't see why she deserves bonus points.
My one change would be point degradation, so that, say, 6 months after a tournament, the points a player earned from that tournament start to decrease e.g. 1000 points from AO. By June, that would go down to 700, then maybe 500 by August and keep sliding until it was worth very little by the next AO. It would prevent one-slam wonders from keeping high rankings for long and would make the rankings a better indication of a player's current form. Of course, it has the same drawback as quality points in that makes calculating rankings a lot more confusing for fans.