let the market decide, instead of being a political decision based on feelings. But that is unrealistic:-(
It's unrealistic because the market doesn't get to decide. Logic doesn't decide on the supply side OR the demand side. On the supply side, the market is controlled by regulations which were put into place because power companies proved they couldn't be trusted to function without them. On the demand side it's limited by physics, power has to get to places before it can be used.
In the USA for example power companies are really only able to profit from new generation projects, so they are motivated to produce the most wastefully expensive projects because when they cost more, they can pocket more of the costs. That means nuclear whether it makes sense or not. And while everyone complains about solar requiring grid improvements, so does nuclear. It represents a large amount of production in one place, so you need a large grid connection to that place. And they are typically not built near other things for obvious reasons, so there's no synergy.
And then of course there's the fact that it's already a requirement to pay the expected decommissioning costs up front, but it's never enough, so The People always wind up paying.