Honestly, doing some research, adults all over the world get more of a kick out of these toys.
Any child that I know, including cousins in my family, aren't fussed about Tamagotchi, but friends I have that are twice as old as I am are still fluffing about with them.
I'm not sure if it keeps us in tune with our own childhood, but even at 23, I love Tamagotchi. It gives you another realm of responsibility as well as they're cute, fun and hilarious at times.
So my thoughts, at least around here in Canada, it's the adults that love these toys. Not the children.