This will correct one fairly minor problem with shooting in bright sunlight: incorrect metering. But it doesn't fix many of the other problems that lead to not-

This will correct one fairly minor problem with shooting in bright sunlight: incorrect metering. But it doesn't fix many of the other problems that lead to not-great midday landscape photos: Stronger highlights suck out color. Highlights on leaves are white when the leaf itself is green, so when you have more bright highlights and strong shadows, the result is the foliage becomes desaturated. Instead of invited greenery, you get a harsh staticky jumble of white and black. Direct light sucks detail out of shadows. When the lighting is diffuse because of cloud cover or a low sun angle going through a lot more atmosphere which then reflects it around, you have beams of light coming in from all different directions. This means more light is able to work its way into shadows. That in turn preserves imagery in there and gives you more to look at. In direct overhead sunlight, shadows are inky black and featureless. The color is less interesting. Overhead sunlight is going through less atmosphere, so it hits the ground mostly white. That leads to a neutral color cast to the image. Angled sunlight goes through a much greater volume of atmosphere. Air doesn't scatter sunlight uniformly and the effect on light depends on its frequency/color (Rayleigh scattering). The sky appears blue and the sun a warm yellow or orange. That in turn means that directly illuminated parts of the photo get a warm cast and the indirect illumination gets cooler. In other words, beautiful warm highlights and blue shadows. It just looks harsh and unappealing. Photos aren't just collections of pixels. We recognize what we're looking at. And humans generally find the angled indirect light of gentle morning on the heath more inviting than the boiling overhead glare of a desert sun. You can take beautiful, striking landscape photos in midday, of course. But you can't nullify its effect. The light you choose will determine the photo. Sunlight is as fundamental to photography as the human subject is to portraiture.