Same reason we don't have a Game.com emulator*. People could make it, but why?
Jokes aside, I've always been curious about at least trying the Tiger handheld 'vanias, simply for the novelty of it. Same reason I want to find a working Game.com emulator to try out their port of Resident Evil 2. I'm sure it'll suck badly. But just curious. I'm all for preserving them for future's sake, regardless of whether or not they're good.
* = There is a Game.com emulator but it's been in beta for a decade now and is completely unstable. The developers have no plans to finish it.