It is absolutely necessary to sharpen portraits, and no. Sharpening and the Clarity slider in Photoshop or Lightroom is not the same thing. Unfortunately, many photographers sharpen portraits globally by using unsharp mask on the entire image or the Sharpness slider in Lightroom. Portraits absolutely require selective sharpening. The eyes and hair should get quite a bit of sharpening, but the skin should usually be blurred rather than sharpened. Take the extra 30 seconds on your portraits to sharpen selectively and you ll see a significant improvement in your image quality.