Proposing nationalization is akin to blasphemy nowadays - way outside of Overton window. But I haven't really heard any good arguments or benefits of electricity production and distribution being private.

On the other hand, there are a lot of good arguments in favor of state ownership - matter of national security, need for redundancy instead of efficiency, it's a commodity and a basic necessity, low margins, large scale leads to financing issues for corporations, chicken-egg problems that state is better at dealing with, the domain is primarily about engineering challenges with branding and management having very limited impact, simple supply chains, cost-cutting may lead to disastrous consequences, etc...