According to the World Intellectual Property Organization copyright law exists
“to encourage a dynamic culture, while returning value to creators so that they can lead a dignified economic existence, and to provide widespread, affordable access to content for the public.”
However, have you ever thought about what it means when instead of giving a publisher a licence to reproduce your work, you give them your copyright? Essentially you will not be able to reprint that piece in your collected works, or include any part of it in related works or put it on your website. You will not receive any fees should it be translated or adapted in any way. In fact to use your own work, you will have to ask the publishers permission and risk refusal! And this is when you will have done all the work and other academics will have carried out the refereeing process. So think about it before you sign the copyright form and at the very least, ask for permission to place your authors version on your institutional repository or website.