Arcanist is a DPS. Summoner is a DPS. Scholar is a Healer.

One role per class/job. I fail to see where you are attempting to go with this. BLU, if introduced, will follow the same format. You can sit here and attempt to theoretically argue how it should not be so it all you want, but SE will keep it that way unless they backpedal on their "one for one" stance. Trying to go against that is really not making any sort of progress on getting BLU into the game to begin with.

That being said, also attempting to theoretically create a class, one has to take into consideration the systems currently in place. If we agree that XI's systems would not work here, than there is no point in comparing the two. It wouldn't work regardless. Stop.

BLU will only work if they add in monster families and elemental spells or let us learn boss abilites to get any sort of variety. Both of which are a bit of a stretch.