The issue is that right now renewables energy don't reduce CO2 emissions by much. (Except for hydro)
Sure if we look at the energy produced it's very clean. The issue is intermittence. As a society we decided to continue using electrical equipment even when the sun is not shining and the wind is not blowing. So we use fossil fuel to compensate and overall the electricity production still enjoy a lot of CO2. We could use batteries, but utility scale battery are not very developed yet.
Same issue with the price. Sure solar energy is very cheap, when it's sunny. But what if I want to turn on the light at night ? The solar panel are not producing, the wind is not blowing, price is irrelevant if I can't get power when I need it.
Nuclear can produce a reliable amount of energy all the time.
I hope we will see the development of utility scale energy storage because this is what we really need for the development of renewable energy.