Eh, I've got my own opinion on how the ATR ended up, but it's easy to go too far in the other direction. How much can you show over the course of a year (implied - or more, or less, who knows) without either running out of steam or ending up showing too much.
Dawn represents the start of the story, and was used for the start of the marketing campaign. Regardless of whether the backlash was anticipated or not, regardless of whether it's deserved or not, it kinda 'makes sense' in a rather straightforward way.
After how explosive the 2013 E3 trailer was I think overall expectations were very very different from what they showed at Gamescom.
Yeah, I understand what Square is wanting to do here, and I get there's still PAX/PGW/TGS/Jump Festa coming up, but I can't help but feel Gamescom was a huge missed opportunity to actually give a good overview of the gameplay, to a worldwide audience.