Friction in government is a good thing, otherwise the will of the few would outweigh the many and catastrophic projects would be allowed all of the time. Yes men could have done it but they wouldn’t maintain it like the beavers and they certainly wouldn’t have done it in a way that fits with natural cycles like the beavers did. This is more of a case for fewer nature altering projects and more restoration of ecosystems
What makes you think the beavers will maintain this dam? Beavers may maintain this for multiple generations, or they may move on next year due to predator pressure or lack of food.
True if the process of selection favors projects that produce the greatest social value, which is far from certain. Specifically in the case of projects with significant environmental impacts, I suspect you are right -- because Earth doesn't usually get a chance to present its counter-argument.
