It is a legitimate question. In the case of these dams, all of them produced very little power for the damage they did to the fishery. They were all old dams from an era where a few megawatts was a huge amount of power.
Correct.
Most all dams like these are licensed for fifty years by FERC. At the end of the license, the owner/operator can either remove the dam or apply for a new fifty-year license.
In order to receive a new license, the owner/operator must make a convincing case that they are still the "best" ones to operate the dam. While I'm not sure what all goes into being "best", I do know that FERC can also mandate costly improvement (such as new fish passage facilities) and/or operating restrictions (such as tighter reservoir elevation limits or flow restrictions) that reduce the value of the power generated. Given that fifty years has passed, it's understandable that these mandated improvements/restrictions can be extensive and costly.
This means that dam owner/operators have to weight the value of the power produced and the costs of FERC-mandated improvements against the cost of dam removal. (Yes, there are instances where dams get relicensed simply to avoid their high removal costs.) In the case of many century-old small dams (coming up on their second renewal), removal is the economic choice.