The fable “The miller, his son and the donkey” tells the story of an old man, his young son and a donkey, who walk from one city to another and no matter how they utilise the donkey (without anyone on it; putting only the son on the donkey; putting only the father on the donkey ; both riding the donkey; etc.), people criticise them for the situation. The conclusion was “Please all and you shall please none”.
How is it important? Some people, especially those that are jealous or envious of you are bound to berate you. You smiled while performing a sad song? Someone will complain. You’re wearing prescription glasses, like I do? Someone will label you as “half-blind”. You wrote some Star Trek fan fiction? Someone will tell you it’s lame. You wrote Chuck Norris facts or lolcats? Ditto.
You're thin? Fat? Chubby? Plump? Look too normal? Someone is bound to complain.
So just be happy with who you are.
Naturally, if enough people complain, and/or you think their criticism has some merits, you can try to improve in some respects (without making a fuss about it). But be happy with what you have and who you are, despite all the haters.