It is actually somewhat important to be able to see Bahamut. He has a healthbar and can die to mechanics, so knowing where he is so you don't nuke him with damage (some things can actually hurt pets) has value. Like I said before, being able to place him would be more helpful than just hiding him from others.
He actually does not have a health bar. Even if he did, being able to place him would make things harder on the summoner. Bahamut delays his attacks in order to move with the player and spending any amount of his 20 second uptime moving is a detriment.

In my eyes the only thing that would stop complaints from other classes is to allow him to be hidden via a setting or to implement a transparency if he is between the player and the camera. The best thing to do would be to have him occupy the same space as the egi when he is summoned so that the movement delays are negated, but unless he can also be hidden he will probably still get in someone's way.