I think one of the biggest reasons Digimon is a failure compared to other franchises is the lack of merchandise. We have a major animation studio and a major merchandiser working together (Toei and Bandai) on something that lends itself EXTREMELY well to merch, but it doesn't exist despite there being demand. Don't get me wrong, there are v-pets, anime, a card game, video games of extremely variable quality, and even some figurines/plushes... But it doesn't exist in the levels the fans want. They cater to Digimon Adventure 01 nostalgia and release a couple of toys for the current show, but then go right back to not existing.
I've looked for merch, and unless you want something that's one of the Digimon Adventure 01 partners, you're almost completely out of luck. Digimon is the closest parallel to Pokemon that exists and you'd think they'd cash in on that and turn it into something more, but it feels like they are reluctant to. After all, who would buy a toy of a robot poop? Except... a lot of people would. There's fans for almost every Digimon created, just like with Pokemon, it's very easy to find ones that appeal to you.
My favorite Digimon is ExTyrannomon, a stuffed dinosaur Digimon. It's been featured several times in the different Anime and V-pets, but there exists no merchandise of it, something that lends itself EASILY to being a plush toy. I know Digimon died in the West for awhile, but it still flourished in Japan... and even they still don't have merchandise. What merchandise we can get is what they've got. Even over in Japan, it's all Adventure 01 nostalgia and a couple of extra figurines. I do not know why something that has so much potential and lends itself so well to fandom doesn't capitalize on it. If I made something even half as popular as Digimon, I know I'd make sure fans can get their favorites from it, but sadly we're just left wanting.
