You'd think fossil fuels would have taught us the value of foresight wouldn't you? Even if you were aware of the consequence of excessive CO2 from the advent of the era, it could easily have been dismissed. 'Worrying about a bit of extra CO2 at the beginning of the industrial age is downright idiotic. There's a
lot of atmosphere around our planet, and a bit of extra CO2 is good for the plants anyhow!'
There's a huge difference in nuclear going from a small chunk of our present day power generation to eras where some see it as being the primary generator for whatever exponential increases in energy we'll be using in the future. This change in scale really should affect how you look at things. Nuclear in particular has some pretty catastrophic fail scenarios, major decommissioning issues, and other problems. These can kind of be hand-waved away at current levels, but can't when you start talking about increasing operations on the order of magnitudes.
And when you start talking about things like this you're also implicitly alluding to breeder reactors, salt-water extraction, and other technologies that not only add substantial complexity (and side issues) but also greatly increase the costs relative to present day nuclear, which poses even more issues in terms of sustainability.
For all intents and purposes solar is pretty much a flawless method of energy production. The one issue is night time production, but there are countless ways to store energy even if we ignore more utopic scenarios like global high energy direct current lines constantly transiting energy to where it needs to go. Given the practically unlimited generation possibilities the loss of energy involved in either storage or transit are not really that big of a deal, and would not affect expected pricing the same way as dealing with nuclear's practical problems of scale will.