Presets and picture effects, such as sharpness and contrast, are only applied to the file types that are 'developed' in the camera, such as jpegs and video files, and not to the raw data that can be saved to the memory card. But even though changing jpeg-only effects like Sharpness has no effect on the raw image, you might still have reasons to use them.
The camera will generate a jpeg image based on your image preset settings, and it uses this to show you the image on the LCD as well as provide information for the Histogram and highlight warnings. Boosting your contrast settings, for example, can make the tones that your camera reports too extreme, giving the impression of exposure problems that don't exist in the underlying information.
Once nice side effect of this is being able to use the monochrome camera settings to preview/review an image in black and white right on your camera, without giving up colour and all of the options it provides in the recorded image. And if you like a particular look that can be set in the camera, but don't want to record it as a jpeg, it will also let you see what the potential result can be.