We are concerned on R&D budgets. Costs matter because costs represents material and personnel that needs to be devoted. We are also tight on time. Nuclear reactors take at least a decade to build.

Oh, and while we have lots and lots of people and know-how in renewables, battery tech and transmission technology. We don't have that many people who can build reactors, due to the anti-nuclear trend of the last three decades. You can bemoan that, and maybe building up nuclear during that time would have been a solution to climate change, but that doesn't change the fact that even if we wanted to build hundreds of nukes today, we would lack the specialists.