To offer a little support for the OP, I do feel that Wizards droped the ball just a bit. I would have been much happier if they had made the custom design rules in such a way that buying 2 of any faction pack would meet the requirements. I would have liked to have seen 2 copies of each order card in a box so you wuld have no card redundancy to get the full playset you may want.
So you want 4 arcane portals and 0 invigorating smashes, just so you can get a full playset of Arcane Portals out of 2 boxes?
There are precious few cards I find myself wanting 4 of, as most cards are only going to get used in conditional circumstances. I am happier getting variety in a single box, customization from a second box, and tournament-complete sets where needed through the secondary market. Getting 2 copies of each card in a box = less variety = fewer net options available in the game on a whole.