Fair enough about wanting at least one USB-A port, but I can't wait to upgrade from my 2013 MBPr to something that charges over USB-C. MagSafe is nice, but the magnetic breakaway USB-C cables look fine too, and it'd be much nicer to have chargers set up all around the house that work for all of my devices and don't cost a small fortune.
Charging over USB-C is ok but MagSafe was better and I almost never care about which side I'm charging on.
So mixed USB-C is the best bet IMHO.