Well, in the trailer I linked ...
And for FFXV, we know a great deal of the first 10~20% of the story just from the 50 min demo reel and also of the Accordo that happens shortly afterwards. I would agree if they could show snippets of random important events out of order then it would be fine. But the fact is we know the structure of FFXV's story too well due to the Duscae demo and other reels, and by releasing anything else ontop of that it may potentially spoil the rest of the story. We know what Noctis's goal is and where and what he needs to do. Never before have we had such detailed information on a FF storyline because Square Enix has had to continuously rework the game. I belive that because we have had to wait for information to slowly come in for the past 10 years, it feels like we know hardly anything about the story, when in fact we know more than we should if FFXV had not been announced so early. And remember back in the days internet access was not so free and easy so they had to make a big blast for each trailer they made. Nowadays information is easily spread and at more regular intervals. Today's crowd is also more spoiler sensitive. You can look at movie trailers in the 80s and 90s where they pretty much spoil the whole movie and compare to to most movie trailers today.