If someone runs with no BRD/MCH, they should know what to expect. Your caster is not your MP battery because they need their MP.
I don't think the purpose of Mana Shift is to be as good as Refresh. It is there to help, but people started depending on it so much. I personally think casters will suffer if they keep it on CD at a higher cost with no BRD/MCH around to give them their MP back.