Here is an article on the politics of big policy ideas. It’s worth reading. As it pertains to the current presidential primary, Warren and Sanders have such ideas. They are needed not only if the country has any chance of addressing the structural problems — climate, wage and economic stagnation, economic and other forms of inequality, etc. — that unless addressed make the future problematic. But also in order to engage the American people and to change their perception of the role of an activist federal government.
I would be happy with either one as the nominee.