Is it possible to change Gamertag?

Hi!

My question is: Why haven't Sony implement a way so you can change your Gamertag?

When I first bought my PS4 and created an account it said your email is already used? Then I did a "recover your password " and it seemed I already had a Sony account. Don't know when I created it but...

Now I have a gamertag I do not like and I know many people have the same problem...