What I think is that choosing a particular shooting mode depends a lot on the scenario. If someone is shooting action full-time like sports photographer, he may well prefer shooting in shutter-priority mode as this mode gives him a lot of flexibility in freezing the action. Wedding photographer on the other hand say has to create a scene with romanticism, soft focus and dreamy effect to perfectly portray the nothing but the wedding scene. Here wedding photographer will mostly turn on the aperture priority mode to introduce soft focus, beautiful blurs, bokehs and the likes.
So in my personal opinion, I think when aperture priority and shutter priority gives the photographer so much of flexibility to get the desired effect, manual mode should be the last option to play around with.