Renewables are great when they can be applied (places like Britain, Denmark and Spain for wind, for example), but issues relating to intermittency and the location of potential (you can only harness solar energy when/where the sun shines, wind energy when/where the wind blows and tides/waves where there are adequate marine currents) mean renewables will never on their own be able to meet all the energy needs of however many billion people live on the planet.
A balanced approach combining both nuclear and renewables is the only practical and sustainable way forward. It doesn't have to be either/or and I don't see why people think it should be.