I must say I'm sort of ambivalent on the issue.
On the one hand, I think it would be cool to see her revise the books, since her writing has definitely gotten better as she's gone on.
On the other, part of the charm, in my opinion, of the books is that you can literally see her getting better as time goes on. Additionally, it's nice that the story starts off simple and gets more and more complex as time goes on - it's a nice parallel to how life gets seemingly more and more complex as you get older.
The cynical side of me thinks she's only doing it for money. Not that I really think she needs it at this point, but there's always the possibility.
The artist side of me sees why she would want to do this - it's a common ideology that a work of art is never really done for an artist. Sure, there's points when you have to just release it, but in reality you're always tinkering.
And then the psychologist-philosopher side of me says that you're never the same person that you were an hour ago, let alone five or ten years. So when you revise something, what you're really doing is re-imagining it through your new eyes.
Then it tells me to commit myself to an institution because I have Multiple Personality Syndrome.
On an aside, I think it would be really cool to see an "Extended" version of the HP movies too, though practically impossible at this point in time.