We could have always just not stopped building them- done a reactor every 5 years just to keep that institutional knowledge alive- but that's too long-term for any modern democracy.
>We can build GW scale solar for a third of that amount already.
No. China can (by dodging all the regulatory hurdles we've so wisely imposed, of course), but we can't.
So we have 2 options- we can either pay 0.5x the money to China, gain zero institutional know-how, and in 20 years when the prices have quintupled need to re-learn how to build reactors anyway... or we can spend 1x now to do it up front, then never need to worry about that ever again, and as a bonus don't need to hedge our bets on future technology for storage.
Going with solar is irresponsible, and its TCO higher, when you're thinking beyond the short-term.