Rune pages should be free; we already pay for runes
Title. It costs between 9300 and 11600 to fill a page with runes. It shouldn't cost five dollars for a page. (and for that matter, the 590 it costs in RP isn't even the right RP equivalent to cost 6300. It needs to be 3150 to be consistent.)
They make their money from skins. If players are jipped 6300 IP for a rune page instead of using that IP for a champion, they won't have a new champion to buy a skin for.
Riot actually loses money with the incorrect conversion, since most skins are 975 RP. I earn a 6300 champion that I like, I'll probably buy a skin. But even if I buy a rune page with RP, they're making less than if I got to buy a champion instead.