@umbra21 - It's probably seen as somewhat negative because of the jobs where women end up being called matrons. They are often in charge of children or young people who are naturally going to resent authority and would not consider being compared to it as a compliment.
I don't think it is always a comment on appearance, but that might be a cultural thing as well. It doesn't seem to be a common word in American English. I have heard of a "maid of honor" more often than a matron.