Adam Clarke on Leviticus 21:17

Whosoever - hath any blemish, let him not approach to offer the bread of his God - Never was a wiser, a more rational, and a more expedient law enacted relative to sacred matters. The man who ministers in holy things, who professes to be the interpreter of the will of God, should have nothing in his person nor in his manner which cannot contribute to render him respectable in the eyes of those to whom he ministers. If, on the contrary, he has any personal defect, any thing that may render him contemptible or despicable, his usefulness will be greatly injured, if not entirely prevented. If however a man have received any damage in the work of God, by persecution or otherwise, his scars are honorable, and will add to his respectability. But if he be received into the ministry with any of the blemishes specified here, he never will and never can have that respect which is essentially necessary to secure his usefulness. Let no man say this is a part of the Mosaic law, and we are not bound by it. It is an eternal law, founded on reason, propriety, common sense, and absolute necessity. The priest, the prophet, the Christian minister, is the representative of Jesus Christ; let nothing in his person, carriage, or doctrine, be unworthy of the personage he represents. A deformed person, though consummate in diplomatic wisdom, would never be employed as an ambassador by any enlightened court, if any fit person, unblemished, could possibly be procured.