The Smurfs stuff literally came out just after the movie hit theaters. I really think Sony didn't have any faith in the movie at all, but took the chance to move it up to July and then everything went uphill from there. Once the merchandise hit store shelves (at least the first time) they quickly disappeared. I went to a Target that had a whole end cap of Smurf figures... the week after the next, the endcap was GONE!
Of course, Sony doesn't have its head up its butt when it comes to Kid's meal promotions, so they had those things there too.
With the Muppets, it's mostly due to retailers and the toy companies. I don't think anyone expected the movie would breathe this much life back into the franchise. It's disheartening to think that the only places you can get a Kermit plush are Disney and Wallgreens. There should have at least been some motley Christmas stuff. But everything is selling out, sending the message that they completely underestimated how well this movie was going to do, and totally underestimated how the merchandise would go.