I didn’t read all the responses so maybe someone else mentioned it but think about it this way…
Imagine you come to this magnificent palace, you go through a beautiful garden, walk passed the fountains through the golden arch into the royal palace. You walk on the marble floor to get closer to the kings chambers and then you see the 2 guards at the door protecting the king and one of them is limping.
Wouldn’t you think that this king could have done better job when hiring guards?
We as humans judge everything we see according to our standards. Hashem wants to make sure that when we bring our sacrifice to a Kohen, who is a representative of Hashem, we shouldn’t think negatively about him or about Hashem he is serving.