I'd prefer them to be mostly municipal or collectively owned by multiple municipalities over making them state-owned. Obviously power generation is big enough for it to be state-owned to be a workable choice.
You have it similar in US. I bet a mayor can build sewers, collect garbage and build a lot of roads without asking the governor or president.
Or did you conflate government with public sector?
And if you underbuild it becomes a problem for the users. And if you overbuild... well, let's assume investors won't let you do that. So, once public sector guarantees demand for decades upfront, it becomes more sensible for it to just have the plant older-built and run it itself.