Why not both? Yeah, dams cause continued ecological damage and I don't think we should be building more of them, but let's leave them in place until they can be replaced with proper renewables.
But yeah, you're 100% correct that that shit should have been nationalized yesterday. Unfortunately all it takes is a conservative-majority (low-c conservative for an international audience) to re-privatize it and let their buddies buy it at a discount. That seems to be what's happening globally. I'm starting to think the best way forward for most things related to the common good are the formation of non-profits or worker's co-ops but that's a non-starter in something as large-scale as baseline power generation.