Well that game was more focused on younger audiences so the merch was geared toward them and the parents bought it all up. As for the games they produced.... They made the same game over and over again with no rooms of expansion except different themes so of course it wasnt going to be top grossing in the mobile market.
I think supercell would be smart just to do select things like clothing, figurines and maybe some lame keychains or something lol... also it's not logical to say that their programmers at supercell are going to design the merch haha.. they would just hire a merch division that would occasionally get a signature from the owners of supercell.

