Why were people with disabilities not allowed to be priests in the Old Testament?

[paul s]

On first reading it looks like God is discriminating against people who have "faults", most of which they have no control over:

Leviticus 21:16-23 "In case there is any man in whom there is a defect, he may not come near: a man blind or lame or with his nose slit or with one member too long, or a man in whom there proves to be a fracture of the foot or a fracture of the hand, or hunchback or thin or diseased in his eyes or scabby or having ringworms or having his testicles broken."

Obviously, God is not uncompassionate, so why this law?
dewcoons - Good answer. My knowledge of the OT is a bit behind my understanding of the NT. I understood the part about them having to be holy (like Jesus was the perfect high priest), but you shed a bit more light on the practical side.

[Zain]

A lame person who was a descendant of Aaron could not serve in the priesthood, although he was allowed to eat from the things provided for the priesthood for their sustenance. (Le 21:16-23) Jehovah set a high standard of physical fitness for his priesthood, for these represented him at his sanctuary. (Le 21:17-23) So, too, Christ, the great High Priest, was “loyal, guileless, undefiled, separated from the sinners.”—Heb 7:26.