"Only has simulators" is very different from "nobody can use". MMIX has value.

MMIX is fully documented, though. Being an educational platform is a valid reason to be supported.

The difference between hardware and software is getting fuzzy (Transmeta, NVIDIA Denver, ...), but there's at least one (admittedly terrible) FPGA implementation of a subset of MMIX large enough to execute small graphical demos: https://github.com/tommythorn/fpgammix