I don't see how you can separate these two when discussing the implications and ultimate meaning of the story. The technology revealed in the final shots is literally where the characters end up, and so part and parcel of what makes the characters' fates happy or not. I don't see anything contradictory in recognizing that from the characters' perspectives (and for the most part, the episode's), it is an unabashedly joyful and heartwarming ending, but at the same time thinking that what's revealed at the end casts some existential uncertainty about the meaning of their decision that the characters are either unaware of or have chosen not to care about for the moment. It doesn't have to be either/or.
Like Vilam, I find the tone of the some posts in this thread, that their interpretation of the episode is simply the only objectively correct one, and anyone who disagrees must be bringing in their own personal baggage (as if anyone saying that can be absolutely certain they are immune to doing so) to be a little off-putting.
I'd say that there's a difference between the episode's
story - the narrative being told via the interactions of characters with whom we empathise to varying degrees - and the
universe the episode establishes in which it tells that story.
I also think the reason for the vehemence with which posters are arguing their stance is two-fold, at least in my case: the emotional high of what is certainly one of the best love stories and happiest endings to anything that I've ever seen feels somewhat sacred. I care about these characters. I empathised with these characters. I saw them drive off into the sunset. The power of the story is such that questioning the happiness of these characters gets in the way of my joy.
"Wasn't The Goonies awesome?" "I guess, but you know Sloth probably rolled onto his back and died that night like the elephant man, right?". In the Gooniverse, Sloth might well have died horribly seconds after the credits roll, but while that's a valid discussion point about the biology of Sloth, it's not accurately pinpointing an ambiguous message being delivered by the movie in order to call the happiness of the ending into question. Feel free to pull on that thread, but to argue that actually The Goonies didn't have a happy ending just seems needlessly cynical.
The second reason is that by every storytelling metric over can possibly apply, the ending is objectively happy. The universe or society in which the story takes place might not be ("what about all those innocent contractors who worked on the Death Star who died when the rebels blew it up?), but this is a happy story with a happy ending; and to deny that feels so utterly absurd that the sheer incredulity begets some very black and white responses. It's not "they're so happy...but ominous machine!"; it's "they're happy, and they're in a machine now. Maybe our souls don't have to be defined by superstition. Maybe they're things we can create?" It's intended to provoke thought, but not in a way that casts a shadow over the tale of its two protagonists.
I'd think that as long as people are debating the issue respectfully, the vehemence of their viewpoints wouldn't be cause for concern - I apologise if anything I've posted came off as aggressive. I'm just utterly convinced of my rightness with regard to this question, and protective of the happiness that made me feel good.
