I browse through Flickr from time to time, just to get an idea of what the average photographer is producing these days. (Flickr has work by exceptional and execrable photographers too, of course. It's just that the distribution matches that of your good old-fashioned bell curve, with most of the work in the middle and the best and worst at either extreme.)
One of the most common failings I notice is an indifference toward light. It's not that the photos aren't lit; it's that the light is so... average, unexceptional, and generally uninteresting. I suspect this is because the photographers get so caught up in the subject itself that they fail to consider the role that lighting plays in bringing a subject to life. It's like the difference between going to a stage play that has excellent lighting vs. the same play on the same stage with the same actors but with mediocre lighting. Sure, the lines are the same, but the emotional impact is considerably less than what it could be.
Some might argue that you don't have much control over how a subject is lit, especially if you're shooting outdoors. My response would be that you do have control over when you release the shutter. Why do it when the light sucks? Why not wait for better light or look for better light? Why not shoot at a time of day when the light is more dramatic, such as the morning or late afternoon? Why not look for or create photographs where the subject and the light compliment each other?
Once you really start paying attention to light you may begin to notice that there are a lot more variations than hard and soft, bright and dim. You'll find yourself using adjectives such as "clean," "flat," "warm," and "cool." You'll also become a bit more experimental with your exposures. The "correct" exposure becomes the one you like the most, that conveys what you're trying to get across, and that packs the most emotional impact.
You may even discover that in great light almost anything you photograph looks fabulous. I'm seldom that lucky--but one can always hope.