I'm supposing that cooperation here is more than trading. Rather, it's the orientation of the game - are you playing with other players to achieve the same goal or are you trying to outdo the players and reach your personal goal?
Catan and all those nice examples of Eurogames do rely heavily on players exchanging goods, but they still try to be the one and only winner, at the expense of other players.
I would argue that Hanabi is not a Eurogame - the only thing that links it to one is the lack of conflict among players (and that common flaw that the theme has little to do with the game). The fact that cooperation is associated with Eurogames is reinforcing a stereotype which is just not true.
I would argue that cooperation is not a specific mechanic for neither Eurogames nor Ameritrash. If you look at the top Eurogames, few of them actually require cooperation - what passes for "cooperation" is mostly exchanging resources so you can continue playing to your own benefit.
Imagination in a game is primarily used to visualize the story and actions, the world the game is simulating, not what the piece is supposed to represent. Having pieces without character is taking the player one step back, requiring even more effort to immerse into the world we're supposed to accept. If I'm playing Game of Thrones and I need constant effort to visualize these: http://s3.amazonaws.
(Kemet figure example) https://www.snakesandlattes.com/uploads/
Cooperation is not limited to Eurogames. Bang is a good example - a competitive game in which you better cooperate if you want to survive! Conflict doesn't mean lack of cooperation - quite the opposite, you're more likely to work together if you have a common enemy (for example an OP opponent)
Good design is a design that gives you a better playing experience, and the problem with Eurogames is the lack of connection between the artwork and gameplay. Sure, Carcasonne "makes sense" in that setting, but so do many other settings (Hunters and gatherers, Star wars galaxy theme... so many variations with the same mechanic shows how little it matters). In short, design is not utilized to its fullest to immerse the player in the game. Meeples are easy to produce and practical, but they're bland and without character. When you take a figure from Kemet - you feel the character, not just of your side, but the character of the game!
Eurogames don't need to be board games: Eurogames primarily function on the principle that you collect points from your surroundings, whereas the opponents are merely racing to achieve a score (anticlimactic?) faster than you. At best, they represent an obstacle the player has to work around, and a potential ally to hinder stronger opponents together. At worst, they're just human difficulty level.
Computer games, on the other hand, have developed enough to be worthy adversaries even in complex games like Catan. A player can have pretty much the same experience of playing Carcassone at a table as they can playing it on a computer. And that's not just a waste of resources, it's a waste of opportunity.
Ameritrash is utilizing the one aspect video games will never have: physical human presence and interaction. By making the challenge focus on opponents rather than a board, the game gives meaning to the other player (rather than them just being, as mentioned, a difficulty level and obstacle). If you see your opponent as more than a competitor for the same goods (wheat, rivers or kingdoms) you can experience them as a person, and not a lever in an open market. And that is the beauty of board games that Eurogames are missing.
