The concept of using native plants for everything from backyard gardening to widescale revegetation is the most important and promising idea in ecology today. It's positive consequences are immense, and we don't even know their full extent. Pruning is also minimal, because natives usually grow to their mature form and then stay that size, whereas hybrid plants continue growing like cancer.
Native flora brings native fauna.
Not only does this mean habitat for human-appreciated critters like birds and butterflies, but more invisible and possibly more important creatures such as insects. California, for example, has nearly 1000 species of bee, many of whom have a single plant species as their nectar source. The need for pesticides disappears. On a higher level of the food chain, small mammals also return. More gophers mean more owls, etc.