Luggage space is the key.
Wife does fine with a 3 series as a daily with the kids but all she can fit in the boot is the double pram and one or two bags shopping. When needing to take more (travel cots, suitcases etc.) my 5 estate was only just big enough so we bought a roof box too, so it was big enough for all their and our stuff including double buggies and travel beds etc.
Sure your can pack light and cram it all in, or you can just get a car with more room and save on the hassle.
This is why I ended up with the Alhambra. And the wife still managed to fill it when going away for a few days.