Nuclear isn't cheaper now, and won't be any time soon. If we want more cheap energy then renewables _are_ the right solution, especially in places like the US where land is cheap and there is plenty of sunshine. It makes less sense in Europe, but if the Chinese make substantial advances in nuclear tech then great — we can build new reactors in 10/20 years when they do make economic sense.

I have no idea how this makes electricity from renewables “higher quality”.

This issue comes up all the time in energy analysis where you need to carefully distinguish between "primary" (i.e., before conversion in a heat engine) energy to zero-entropy energy (electrical energy, work).

When people are talking about 1 GW nuclear reactor, they mean that reactor is generating 1 GW of electricity, so that the reactor is in fact >3 GW thermal. Nobody is comparing electricity from renewables to thermal energy from nuclear.

In fact, this actually makes nuclear superior: you can use the waste 2 GW of heat to run district heating in nearby located cities. Pretty popular in Europe, though with coal/gas plants. There is no similar useful byproduct to solar/wind.

Of course the sun does provide direct heat without need to process it through panels. Solar PV and nuke customers both rely on that.

If anything, a "higher stage" of civilization would be perfectly sustainable and highly energy efficient.

There's nothing civilized in being a parasitic species.