Re: 3e Spelljammer Cosmology (part one - terminology and crystal shells)

I think your cosmological work is very good and very logical in terms of
(3e) D&D.
Do you think, though, that the Spheres, phlogiston and so on are elements
that Spider Moon deliberately left out, ie as part of the Polyhedron
approach to old "unpopular" settings? Do you think they meant that now the
new version of SJ has no spheres, phlogiston and so on? If so, how would you
handle a realistic universe of solar systems with simply magical propulsion
and spaceship design?