I think linkexchange is still important because it is a vote for your site. I Do no think it is a waste of time. If sites have a similar theme the number of these votes are important for SE ranking (if they are relevant to your theme ofcourse).
But like Simmo said content is king and it will be for a long time.
We all would like to have super unique and sticky SE content.
But let’s face it with so much competition, your site must be an authority if you can say i do not need linkexhanges.
Rick