Why not make Omnistone like unsealed spellbook and u get to choose which runes u cycle through

Why not experiment with this concept on PBE or something. Most people agree Omnistone is a sub-optimal rune basically no matter what since champs are balanced around rune keystones. Making it random was a nice idea in theory but in practice it just isn't working. This new omnistone will be like spellbook in that you get to choose which rune, and much like spellbook you cycle through them once you use the rune, and can't use that rune again until you've cycled through all of them. Enemy champ low? Go dark harvest. Jungle about to gank and u have cc? Go aftershock. Need damage and sustain for extended fights? Switch to Conq. Want to gank a lane while your lane is shoved? Go predator. You see the idea. And you can't use it again until they've all been cycled though, thoughts?