Just my opinion, but I noticed Disney films (and even other kids movies) choose to present parental figures as non-threatening and non-sexual. Perhaps because this his how pre-adolescent audiences perceive their own parents, filmmakers think by presenting parental figures in this manner makes them more palatable?
Also, genetics can be such weird thing, but I would assume a man who fathered a beauty like Belle would be reasonably attractive himself - perhaps looking like an older version of Gaston or Prince Adam. She could, of course, received her beauty from her mother; however, I would still assume her father was average in height and build, and not unusually short the way Maurice was. But going along with my other point, perhaps it is easier to make the distinction between the parental figure and the love interest by greatly contrasting how they look.