Live View is a critical tool for macro and other situations when you need precise focus. Live View uses Contrast Detect AF - a more precise but slower method than phase detect AF used normally. With Live View you can magnify the image to examine areas for precise focus.
The goal with the Live View display is to give you something you can see rather then precisely previewing your image. This enables precise composition and focus. Even if exposure was correct, none of the LCD views are precise. The histogram is much better to judge exposure.