When your simulation respects actual physics, one solar system is plenty.
Something like an officially approved package would be extremely convenient to have, especially if approval for updating said package would also be centralised.
and there's no good reason not to have dwarf planets...
It's doable, but "official" means bureaucracy and it would complicate things.
In the case of my 2010 bases, I simply donated them to the Doctor and Orbiter, and most are now part of 2016.