I can see where you are coming from and I do agree with your setup as it makes sense for you.
I just love to use all of the features Apple offer and I'm disappointed that I can't use this one and when Apple Music comes out we will all be paying more for no real reason apart from the fact that our family is older.
Don't feel too bad. My younger family shares data at home (Comcast 300GB limit) and mobile (AT&T 15GB limit) and they use every bit plus each month. I'm not saving money at the end of the month but I'm trying as hard as I can. Ha.