This has in fact been suggested in the past several times and it was said that this suggestion would be taken into consideration for the new website. This doesn't mean they will actually be implementing it, but it is noticed and considered. All you can do is wait whether it is featured in the future.
It's a good idea and would probably help people get a proper rating if someone just spam rated their game and then went back and actually played it to rate it.
good idea but 99% of people would click it 1000 times just to get some ap i see where your coming from maybe you should only be able to change it once
Oh no no no, it wouldn't be so that you get more AP every time you change it. It would so that you get AP for rating it the first time and you could change your rating if you have a change of heart about the game without getting more AP.
IF this were to be implemented (I don't know if they will GoM, but that's always a surprise!), I think (more probably: I am certain) you would not get any extra AP when changing your rating, because that would be like throwing a stack of meat in front of a pack of hungry wolves... na-ah... (O.o)