Why can't we choose our adaptive stats? I want to build AP items without having my adaptive switch.

I want this to be a legit build, and not troll, on someone like 
But because this switches my adaptive stats from AD to AP (Nashor's tooth gives more AP than Botrk gives AD), this is essentially a troll build because I lose more than I gain by building Nashor.
https://i.imgur.com/E9gpEjc.png[]
I did it anyway cuz I was so far ahead (and I only completed the item as the nexus exploded - and coulda went triforce instead if the game turned). But I want to be able to legitimately do this. Not just "lol we're stomping so whatever."
Let us choose our adaptive stats. Let us choose from 3 options (in our rune pages perhaps?)
- AD
- AP
- "based on items"
So we can lock it to AD or AP, or have it act how it currently does, and change based on items. Just let us choose.

