how critical is passive stability?

Fog??? It's not a question of being " held down." That
does nothing for our muscle/bone health. If that was
the only problem, velcro treaded boots and walking
surfaces would be sufficient. We need the rotational
acceleration to provide enough stress to maintain our
1-G muscle/skeletal structures until we can maintain
that health with drugs, genetic manipulation, etc. I
expect we will wish to maintain our options to
return/visit high-G environments like earth/mars, etc,
for the foreseeable future and the ONLY way we have of
doing that at present is with the rotating structure.
Perhaps our future will provide artificial gravity,
but I expect we will have been building space colonies
a long time before that becomes technically feasible.