Hmm. I thought it was for the new lights, so they can get exotics too. But now that you told me that you first have to unlock them: it's pointless. Unless lets say you want a certain exotic with good stats. Normally you have to wait till it drops, but world drops and sectors also dropped other exotics. So you had to wait untill that certain exotic dropped and also had to hope for good stats. Now you can choose that one, so you have a faster chance for good stats. That is: if the engrams give higher stat ones. Which i dont know.