If you want to know their reasoning, you'd have to ask them, but they don't usually tell the playerbase the reasons why things are the way they are. But if you want guesses as to the reasoning, my guess is they knew most newbies would want to "visit Earth" as soon as possible, so they made sure that you actually have to play the game for a bit before you're allowed to visit Earth. Gameplay incentive.
I suspect the Achenar and Alioth permits were added merely in the name of "Balance"; if the Fed capital is permit-locked, then we'd better make the other two superpower capitals permit-locked, too.