> One of the principal reasons why I love Arch is being able to have a say in some of these base matters

Exactly, Arch allows you to do many bleeding edge things. An installer would never keep up are give you that freedom.

> I remember when Ubuntu supported root on zfs but the installer didn't it was rather involved to get the install going.

That's why many installers allow you to drop a shell when it's time to partition.

> I would have to look up the correct incantation to get the wifi connected on a newer PC

To be honest that would largely be helped if archiso would start using NetworkManager