When using film I frequently used polarizers to deepen the sky and reduce the highlights for landscape shots around the beach. I know that they provide great flexibility in reducing the reflections but are they necessary if the primary use is to saturate the sky and bring out the clouds? I usually follow the philosophy of getting it right in the camera and minimizing the post processing . Interested in some viewpoints.
You should continue to use a polarizer for digital for the many reasons one would apply one (sky intensity, foliage saturation, glare reduction, ND, etc.).
Film-versus-digital is not any different. There is no computer-based post processing algorithm (yet) that has been able to replicate in software what a polarizer does.