No, please NOOOO! Don't do it!
If you do that champion mastery will lose it's meaning, because champion mastery is supposed to show what someone is playing most of the time and at which champions someone is good.
ARAM (all **RANDOM** all mid) is map where you get random champion and not the champion you want to play and if you don't care about what you are playing anyways then you shouldn't care about champion mastery points as well.
Edit: Let's start haters! Hide behind your downvotes without discussing why champion mastery is good/bad for ARAM. Haters gonna hate :)