I remember a flight from NAS to LUX back in the 70s when, due to fog, we diverted to FRA. At FRA pax were given the choice to either get off and make their own way by ground transportation or wait it out with the crew for a wx improvement at LUX. It was also made clear that if wx improvement didn't come about within the next x hours (can't remember the exact figures) they would be transported by coach to LUX. The point was that pax were given a choice.
Giving the passengers a choice is probably the worst thing you could do. If let's say 50% of the aircraft opted to offload themselves and find their own way back, you'd then have to spend forever and a day shifting through 400 bags to find the 200 who have offloaded.