Why are we stuck in one tree in the secondary? (READ)

I feel like the new runes would be mich better optimized if we were able to pick our 2 secondary runes fromcdifferent trees. Why are we restricted to just one tree? It doesnt maokai sense to me.

I think itd open a lot more interesting build paths because as of right now whichever secondary tree you pick theres always 2 runes that are picked over all the others regardless of any circumstances; eg your champion, the enemy champions, your team comp, lane match up, etc. I know this isnt always the case but for the majority it is.

I dont see how this could be harmful in any way and only see benefits.

PLEASE GOD LET THIS THREAD GET SOME RESPONSES I ALWAYS POST GOOD BUT MY THREADS ARE ALWAYS DEAD. LET THIS ONE SURVIVE AND THRIVE!