Not a good idea, for one thing it is against the law in most states.
If you do not manage the composting process correctly you can transmit pathogens that are dangerous to humans.
I wonder if we are ready for taking care of our own humanure in other ways that would be considered a "regression" in terms of urbanity, progress, etc.
Vancouver's CK Choi building has public composting toilets.. it's pretty modern looking. Probably depends on how they're designed.