I agree that the specific situation isn't necessarily as extreme as I painted. (I do like my hyperbole.)
Nonetheless, the underlying message still rankles. I'd have been a lot more sympathetic if the colony ship had stayed on the planet and the main characters spent a lot of time looking up at the stars and yearning. Who can't understand regret and missed opportunities? It's the way the story as a whole - the narrative structure of it - supports the idea that heading off further into space for no damned good reason is a good and noble action, whereas staying would somehow be terrible. (I'm thinking specifically of the part where the man from the planet arrives breathlessly ready to fly off with the ship full of would-be colonists. That's a pretty clear "what they have > what you have" statement on a symbolic/thematic level.)
I dunno. Maybe I'm just not a "colonist." If I arrived to find a fully functioning planet, my reaction would be "Woah, sweet! Awesome! Dude, the human race pulled it off! Woo!" I'd be fascinated to re-integrate into the culture again and learn all the new things. Instead, they act like someone peed in their Cheerios. I don't grok their instinctive response, and the structure and ending of the story tells me that because I don't, I'm not as good as they are, not as brave and noble, not a member of their elite class of mind that resents other people doing well or whatever. (<- editorializing)
The closest analogy/explanation I can think of is the attitude of athletes towards non-athletes. I have no interest in sports. None. I enjoy competition, mind, and I love to play board games and so on, but I don't have some burning desire to win at all costs, to defeat my opponents and see them thrown down before me. (Like, I love Magic: The Gathering, but I've never played tournaments and don't understand those who do.) The vibe I've gotten all my life (from commercials, from my father, from coaches, etc.) is that this desire to win at any cost and be BETTER is inherent in the good athletes, and moreover is Just and True and Righteous, and it makes me feel small and worthless because I don't have that need to be BETTER expressed in that way.