The only camera I use is the event camera and that is just because I think it is soooo cool to see my torpedo run and watch the rusty hull loom into vision.
From a realism point of view I should not use the event camera, but it is just that cool for me
I have never used the external camera primarily because it seems to be very unrealistic and gives information to me that is not "appropriate" to the simulation.
However, I will never look down on anyone who uses this function. Your game is your game.