As a photographer, you won't have them on most of the time. It "taints" the image too much, JPEG more or less force you to do it right and be conservative.
If you are shooting with a 5D III you are going to be shooting with some combination of settings for contrast, saturation, color tone, and sharpness. It's up to you to decide which settings to use. Should one desire to alter the image so as to make your subject appear a certain way the settings are available to do so - on a 5DIII it's just menu->picture style and select a style you've pre-defined for contrast, saturation, color tone, and sharpness. That was the point. Now if you need to supply work for Time and Newsweek perhaps you have a custom setting for each one. Unfortunately I don't think there is a way to bracket between your custom settings. I'm picturing Reuters dealing with a bunch of Instagrammed images and thinking this is going to solve their problem.