Runes were meant for experimentation and innovation
How many people out there actually have enough IP banked up for them to feel comfortable experimenting with runes?
I mean, sure, the IDEA of the system sounds great. The competitive minded can run all the standard setups to get through the game, individual players can switch out some or all runes in a set to get different bonuses that their playstyle favors, etc. The system allows people to run full pages of AP on LeBlanc to instagib people with 50+ AP at level 2, or take crit damage runes on Ashe to randomly do 200 damage with her passive proc at level 1.
The reality is, Runes are simply too expensive for me to want to experiment with them.
Buying a set of 810 IP reds/yellows/blues costs 7200+ IP. For most players, 7200 IP is a month's worth of grinding normals and ranked. If I buy a champion with that 7200 IP, at least I'm getting a completely different experience than the champions I already have. Spending it on runes just feels shitty, especially since I know that if my rune page doesn't work out I just blew a month of grinding for nothing.
I understand that the second purpose of runes is to be an IP sink for veterans, but surely we can think of other ways to reward people who already have everything without making experimentation feel like investing your life savings in a lemonade stand.