The thing is: The "carrying enough troops to put down any rebellion in this subsector" was off even then, considering how large world populations are.Yes, if you read through Adventure 1: Kinunir, you would think those ships are some of the toughest the Imperium has to offer. And back in the small-ship universe of 1979 or whenever, I suppose that was true.
For a proper frontier feel, possibly including a small ship paradigm, slashing all world populations by a factor of 10 might be advisable.