I have a much different perspective, actually. I am something of a Muppet completist, meaning, I try to buy EVERYTHING I can with the Muppets on it. (Yes, it's exhausting & expensive...)
And there's more stuff out there right now than I can keep track of. The Disney Store has released 9 plushes, 4 mugs, 5 t-shirts, and a few other items. There's the makeup and the fingernail polish. There's all kinds of PJs (for adults & kids) cropping up at places like Target & Walmart. There are all of the keychains, Kermit and Animal watches, and slippers at Walmart. There are the FAO Schwarz puppets. There are the iHome MP3 docks & headphones. Singing dolls at Walgreens. Ornaments at Urban Outfitters. JC Penneys has some watches. Kohls has some more shirts. There are more and more shirts online. 2 different Snuggies. New Adidas shoes. Etc, etc, etc.
So, there IS quite a bit of stuff out there -- with more coming, I am certain -- even if it's not necessarily the stuff we'd all like to see (i.e. toys, pvcs, etc.)
But it's not as simple as just pointing the fingers at Disney, either. I know for a fact that some of the larger retailers declined the opportunity to carry Muppet plush. There are lots of moving parts. I honestly believe that Disney wants to make more stuff -- and will, I can almost guarantee, if the movie is a success.