New reactors are expensive. New reactors are late. New reactors can basically only be built by nation states but not privately. Nuclear is not insurable. Nuclear produces waste with excessive half-life. Nuclear steals resources and mindshare from other options. Nuclear energy output can't be moderated well (basically for economic reasons, it runs full steam all the time and for safety reasons, you can only moderate output a little), so it does not effectively augment wind and solar, rather leading to wind/solar having to be turned off.

Wind and solar meanwhile can be built cheaply, quickly, privately, locally, site sizes easily scale between kW or GW of output and they only produce a little regular waste at the end of their life. (Okay, granted, Neodymium mining does produce some nuclear waste too — but definitely nowhere what uranium mining produces.)

Wind+solar+hydro+better national/continental grids+batteries+flexible demand is a much better combination.