I think it's fine to reveal stuff in advance of release as long as it's finalised and in the game. I'm not against marketing per se, I'm against dishonest/speculative marketing that may mislead the consumer.
So you are fine with releasing info but only if it it Finalised? That means you are NOT fine with things being revealed in truth. There is a ZERO guarantee that and feature in development will make it to gold. Developers don't know in advance what things in development will become problematic. They don't know what features they want to add and have prototyped fail to work in the end.
By your standards of what is acceptable for a reveal is there is total silence until a game goes gold aka about 2 weeks before a release. Because that is the only point when a developer "Knows" what features will actually make it into the game.
When developers reveal something in early development they are doing so honestly and they tell players things are subject to CHANGE but its people like yourself that refuse to acknowledge that a trailer and preview of a game in its early stages doesn't mean you will get what you see. What you are getting is a snap shot of the game at that moment in development. Developers have no idea what the future holds they don't know what issues or bugs in a system will derail development and force a change to features.
It is typical gamer unreasonableness rearing its ugly head again. Gamers demand info but when they are told we have no info to give you that we can guarantee will make it in the game they are accused of hiding things and not communicating with their fans. So they then say okay this is what we have at this moment but please be aware this is SUBJECT to change. And when it does change gamers rage at being misled. How were they misled? They were told this was subject to change. where is the duplicity? No one was lied to, no one was deceived you were told the truth and given a glimpse of the game in an UNFINISHED state as it was at the time of that reveal.
Maybe gamers should stop blaming everyone else for their own failings. And yeah if you are told something is subject to change and you REFUSE to heed that warning then the gamer is to blame NOT the developer.