I wish you could change them on the fly too. But that would mean purchasing rune pages would be less necessary so Riot probably won't do it.
I'm guessing that's why he said if he has 20, which is the max. As in, only people with 20 are allowed to change them. --- http://i200.photobucket.com/albums/aa99/VinceYoung_10/random/035.jpg http://www.xboxlc.com/cards/blueice/Why%20So%20FeaRious.jpg