I suspect it's because a lot of people don't see climate change as an actual problem to be solved as effectively as possible, but rather as an opportunity to effect the kinds of change they would favor anyway. It's "never let a crisis go to waste" thinking.

We could even keep generating power with natural gas and just capture all of the carbon emissions at the powerplant. Nuclear is an improvement but you don't even need to go that far if you are serious about decarbonizing the power grid as quickly as possible.