Interesting. I didn’t originally have a preference one way or another for this aspect of Rogue One, but put in this light I can see the issue.

I agree that the Death Star having an intentionally designed weakness does imply that without that weakness the Death Star would be impervious, and this does weaken the message of Star Wars a bit. I think the intent of the Rebels finding a weakness in the Death Star is to show that no matter how impressive a Technological Terror may be, it will always have unforeseen weaknesses.

It feels a bit like the rules of argumentation - you always want to address your opponent’s argument in its strongest form. If the argument has been intentionally undermined, say, by someone on your team giving the opponent faulty data which you can then call out - then it doesn’t feel like winning the argument on its own merits.