Well, first off, the crews inside should have been monitoring their air prior to the low air alarm sounding. What if they were more than five minutes into the building?
My department practices calling for a relief crew and having them meet up with the initial crew at this point. If the fire is under control we have the relief crews meet up at the nozzle. This way, the officer of the initial crew can give a better update as to their progress and what needs to happen from there.
It does not make sense, unless an all out is called, to bring the hoseline out of the building when switching crews. It's the same reason we teach search crews to leave a tool at the furthest point they make it into a structure. That way, they can tell the relief search team to "continue the search from my halligan".
Just out of curiousity, what was the reason you were given when you questioned that call?
We generally do the same thing that you want and everyone else has mentioned. Leave your line and switch out, whether it is outside or at the nozzle makes no difference to me. All comments have made sense when it comes to knowing where the attack left off and so on. At the same time why are you going to duplicate the efforts of the initial crew? When the initial crew is done there is no need for your replacement crew to get their butts kicked by stretching a line in the exact same place. Its kinda like throwing a ladder, climbing it, and taking it back down knowing someone is waiting to right back up it. Just my opinion on the issue. Good luck Paul