The other thing that people forget is that dams, in almost all cases, have a finite lifespan. Both the engineering and (mostly) the silt buildup mean that every dam eventually has to come down or otherwise be involved in a massive infrastructure project rivaling the cost and complexity of building a new dam.

Silt buildup is a trope that often gets repeated as a reason for tearing down dams, but it has no effect on power output. Generating capacity is determined by vertical pressure head, i.e. how far the water drops as it passes the dam, and not by how much water is held by the reservoir. It's factually incorrect to say that silt buildup causes a decrease in generating capacity.