Hydroelectric power generation is by far the most efficient method of large scale electric power generation. See Comparison Chart. Energy flows are concentrated and can be controlled. The conversion process captures kinetic energy and converts it directly into electric energy. There are no inefficient intermediate thermodynamic or chemical processes and no heat losses.
The conversion efficiency of a hydroelectric power plant depends mainly on the type of water turbine employed and can be as high as 95% for large installations. Smaller plants with output powers less than 5 MW may have efficiencies between 80 and 85 %.
It is however difficult to extract power from low flow rates.
Most of the dams being taken down produce little in the way of electric power and some of them have come to the end of their useful lives. Those dams can be replaced by other power generating technologies for less than the cost of restoring/ repairing the dams.
Just the existence of a dam creates wealth. Houses here go for 60 or 70 grand more than larger homes a half mile away because we sit on the lakeshore.
The guy who runs our little party store is considering opening a small bait and tackle shop due to all the fishermen coming into his store.