Just watch SW ANH again. Vader and co don't know there is something up with the Death Star but they still want to prevent the plans falling into rebel hands , Motti is over confident, says it would be a futile gesture no matter what technical data they have stolen etc. Yet they know the rebels have risked everything to launch the attack and escape with the tapes. So that now kind of says to me that the info on the port may have been deliberately concealed so that even when the Imperials immediately review the data on the DS after the raid, they still don't spot the weakness. I mean everyone has taken the proper p*** out of the fact that a small thermal exhaust port (and TWO photon torpedo's ) gets the DS destroyed . This solution just appealed to me in the light of all the info that's now revealed in the trailers and characters.
Given the very short time frame between Leia returning with R2 and the attack on Yarvin the rebels suddenly find that weakness????? How? Are they like Death Star experts? Like you said it could have been previously spotted by the engineering team or it could have been a design flaw introduced that they made even more accessible (like not welding a steel grate over the top of it) by default. I don't really mind as long as the story overall makes sense and it delivers a good film. It never needed to explain itself or its physics, only in the broadest plot strokes because its just a STORY, all be it a very imaginative an exciting one. I love SW for many reasons, one of the strongest being it just looks like a fantastic sci fi exaggerated space opera, which this new trailer seems to more than promise. It may be hard for some here to remember but when I was a kid, nothing, I repeat nothing apart from 2001 (and CE3K) ever looked any good on the screen. SW changed that forever and I will never forget it for that powerful effect that, having watched that new trailer today, is like watching your best dreams come to life and still thrill me forty years on.