Well, I suppose that one big difference to the afore mentioned RPGs is that Starsector will not focus on pre-made quest lines. So while the RPGs herd you across the entire game world on a regular basis, your activities in Sector are more of a choice and can be more local. Or, if you want to make a long journey, the journey itself will be the quest.
Well... talking quite long-term here, mind you... it needs a capstone series of quests to win (or at least arrive at resolution, ala Fallout series) to really be the classic open-world RPG. Kind of like Freelancer in that regard; it had local quests a-plenty, but they were, well, all about money and buying the toys, not about winning.
Hence at some point, we'll almost certainly have to do a lot of FedEx shuffling and traveling about. Then there's the favorite activity of many- roleplaying a trader or building a trading empire or just exploring for the sake of it. Travel, travel, travel. Having to re-cross the Sector because you didn't explore 50 Systems in one corner of the map during early game, for example, sounds pretty grueling.
Stuff to keep it from becoming "OMG, how many hours of my life have gone down the drain watching my sprite crawl across this screen" is important when we start having a big enough scale, basically.
In Star Control II, this was resolved with the gate / wormhole system to some degree (although I'd like to argue that it was less fun than really exhausting for new players unless they had a guide to where the holes went sitting in front of them all the time- the map UI should show these relationships clearly, imo).
Anyhow, Alex, don't think of any of this as critique- what we see for travel right now looks great for local exploration of the Sector. Just thinking ahead about the issues involved in getting it the last few miles