It's just Bungie responding to the people who say that exotics are too easy to get and they want to slow progression. I do understand that most exotics aren't always worth the exotic name anyway, but my thought is that it's a try to preserve destiny. I don't really care about it since I have all the exotics available from drops and I'm 400 on all characters, but others won't be very happy about it. I didn't find a need to do it since most would rather have 3oC, but it's bungie's game so :/