Bungie should play Borderlands 2 to see what leveling and exotic weapons should feel like. To be clear, I really enjoy most of what Destiny has to offer. I feel that they've missed the mark on what is going to encourage long term gameplay however. In any game that requires this kind of time investment, you need a tangible reward. That usually comes by providing your players with a sense of progression (power). The restrictions placed on higher level characters in lower level areas and nerfing high end gear negates this sensation. Before long you have a group of people asking "why am I doing this? What is it doing for me?" If there is no reasonable answer (a compelling story for example), expect them to move on to something else.