As in many areas of design, the less is more approach works much the same way with outdoor lighting. Subtle lighting feels calm and creates and atmosphere. Too much lighting can feel unsettling and out of place. Trees should have a hint of light coming off the canopy to fill the space underneath with a glow. Walkways should have paths lights always forcing light down along the path and should be staggered 8 to 10 feet apart. I love using a few path lights in a perennial bed so at night that purple glow of lavender catches your eye. Not every tree has to be lit up and not all trees should have the same wattage. That balance of distributing light correctly is what makes an entire lighting project come together.
Finally, I love having outdoor lighting for security reasons. It feels comforting to come home late and being able to see the house clearly.
Because LED technology means life long bulbs and fixtures it's an expense that means no maintence and no relpacing bulbs that burn out.