I like the idea with the large mass, because there is also the think that you can now build multi structure stations,
with the new docking system.
I build curently a station wich is 1000m hight and 200m diameter with a big hangar door on the top and in-station dockingports, and to make it round and to use Gravity on all 8 sides, I use 4 sides on the main staion part and 4 sides on 45° angeled rail rotators.
And what if you want to build some rotating wings on your station, this will also be a docked entity.
So currently there is no posibility to build Factories on these Station parts, because they count as "Ships".
So for these things we need Ship factories!
And the idea of making them very heavy is no problem for moving station parts, such as rings, because you dont want them to rotate very fast :D