of course it's worth. the new system won't start before preseason, which is about half a year away. if you want to play AP Aatrox for the next 6 months, then you're more than welcome to do that (unless it's in my ranked games..). 3 pages will fully do for you if you only care about generic stuff. you can't do wrong with Armor yellows and MR blues. then,
page 1: MPen reds + AP quints
page 2: AD reds + AD quints
page 3: AD reds + AS quints
with that, you can literally play all champs in the game.
oh, and from what i know, rito is working on something for exchange for those who spent IP on runes so far ... which means for pretty much everyone who is Lv20+ and started getting Tier3 runes.