They're all able to make planetfall though, aren't they?
I think the idea is that they can, but they can't do anything there. (And I believe exit velocity is intended to be a pain for all of the big bois).
IE if the bigger Hull spindles are expanded with cargo then they can't land etc, nor load up at ground bases. So there's been talk of SRV taxi-ing of cargo from orbit etc etc.
Currently, though, it's all just talk and bug-splosions