Debian needs to stay sturdy, serious and boring. I like my home server running steadily without having to worry about some edge stuff breaking it - I don't need fancy, I need reliable.
You want a flashy/niche distro based on it, they are plenty out there, for just about anything you fancy, in any flavour possible.
The landscape of Linux distros would be nothing without the solid foundation that is Debian. However, with most other forks using their flagship distros as a showcase, why doesn't Debian?