I also have several thousand decks currently, and probably add an average of 6-10 decks a week to my collection. Of course it would be cost prohibitive for me to store everything in brick boxes like this, but even with my favorite decks, I'm constantly reorganizing and reshuffling as I add new rare (for me) decks, as well as multiples of my favorites. I use the large clear plastic "shoebox" like containers with snap on lids from Target. Easy to see, easy to access decks, easy to store. My prblem with a brick box (at least a non paper one) is that it would add bulk, and then I'd have to pind a way to store them. It's much easier to stick a single deck here or there than it would be to try to get a container to hold multiple brick boxes. now what I would really like to see are storage containers, flat, that would hold and display 4, 6, whatever decks flat. Something with a hinged lid with a glass or Lexan window. Something really classy looking that I'd be proud to show on an end-table or in my game rooms or something like that. Something affordable, not a $200 case. Something taht I could buy multiples of. I know that's straying from your question a bit, but I don't think that brick boxes, even in an inexpensive cardstock form, are very popular with folks. If they won't buy the inexpensive version, it will be tough to get them to buy a more expensive version, at least in any quantity, if that's what you're going for.
Maybe a nice quality brick box with that same clear window lid, to display the contents. A nice, furniture-quality piece.
Random thoughts, hope the info helps you. Take care.