We don't know enough about ARR to make that call. If something was OP, they could change the functionality. Make Mute slow spell casting etc.
You could say that about any magic. Through this logic, RDM is unnecessary because it only uses Black and White magic
We're past current. Once ARR is released, then you can make calls like that. If it does turn out to be the case, it will have to be tweaked, like BRD was tweaked.
The flexibility is limited to the devs competency.
Through this logic we might as well not add any new mage jobs.