You don't see physicists going around saying h is wrong and h-bar is what they need to use. Sure they do—or at least, they did. Physicists realized that h is "

You don't see physicists going around saying h is wrong and h-bar is what they need to use. Sure they do—or at least, they did. Physicists realized that h is "wrong", i.e., confusing and unnatural, because it's off by a factor of, um, 2 pi. They introduced h-bar precisely to rectify the problem. And the substitution worked: if you open up a standard book on quantum mechanics, the ratio of uses of h to h-bar is just about epsilon. (You'll also see lots of (2 pi)s.)