cost and not really advertising is probably why they haven't sold out yet. Also contribute the horrible ad for these on Topps site as WackyGarbage pointed out. He's as confused as everyone else about these. I'm sure they will be sold out soon.
I think once we get these in hand people will be pretty bummed they didn't get in on these.
Brad, I'm basically doing what you had suggested before, that is, giving topps the benefit of the doubt and making sure I get the first release in my hands and then decide for myself whether the binders are worth the money, and worth buying series 5 thru 16. I can always blow them out thru ebay & not buy the rest of them if they aren't good & still get most of my money back. But if they are killer, I sure don't want to end up paying more on ebay than topps is asking to get a set because I didn't give them a try.
With all this speculation I can see that if the binders aren't really cool, no one will want the rest of them and the release will tank, but if they are awesome once people see them, it will be competitive to get the rest of them from topps, and those that missed out on 1 thru 4 will be at a disadvantage.