I don't think it helps much to announce a game well ahead of it being shown at all. Games look ugly and broken very early on in development, so if you just showed a logo 2 years ahead of time, and spent that marketing money, would it be worth it? I'm not sure. People may just forget about it, or post "what ever happened to ____?" threads. Not seeing a game for a long time after announcement might have people lose confidence in the title, because it's taking too long.Do you think the industry could shift in that the existence of the product is announced well ahead of time and the peak excitement is the first trailer/media?
People generally don't know how games are made, so they don't realize that the game is going to take a really long time to get made, even in the case of small indie games. It makes more marketing sense to announce it closer to release, when the media they can release is indicative of the final product, and that excitement can directly lead to sales in the long term.
The Marvel example is flawed, because they're the biggest game in town for movies. Not all studios can do that. If we announced 5 game titles with no screenshots, and spent money on the announcement with nothing to show, people would ignore us, and we would've wasted a bunch of money on promotion.