If you have a good developer and a nice budget to hire him, then you are able to clone every exchange/website/program that you would like, but yes, maybe you are going to face some legal issues if they discover that you have copied or cloned all their files instead of creating a copycat.
Just be careful, i think that you want to copy this in order to run your own exchange.. but if you do this, a lot of people will think that you are running a fake one because it would be shady to open your exchange and see that it looks exactly like etherdelta.
Ya and trust is the uttermost important element for an cryptocurrency exchange , I didn't plan to just copy etherdelta
, I'm learning to become a developer so I want to experience different project development , if ethereum , dash etc is open for copy , I would try to copy all of them