I think that we shouldn't be too sensitive. It's pretty normal in my eyes that not everybody likes facial hair and they don't have to in my eyes. Why should the whole world have the same taste like I do?  All comes down to the question how it is presented though. If a friend of mine gets a new haircut and I don't like it (= think it looked better before), I feel most times free to tell this as well - not rude of course. So, I have to accept as well if somebody says that she/he liked the beard/stache shorter, different, not in general or whatever. Patrick has made correct suggestion above to just reply then that one has chosen this look on purpose and that this is all what matters. If a (especially close) person keeps on telling this over and over, it is time to react a bit more "frankly" though. That's it, just relax.