Basically the rewards. Just not worth the effort. Most of my regular friends have gone away from Destiny, so for the time to look for a team, set aside a few hours because it has to be done in one sitting start to finish, get adjusted to working with different people, then get slapped in the face with no elemental drop, just not worth it. It is an all or nothing proposition and there is a high chance of getting nothing.. At least in VoG there are drops at different points and you at least get something useful. Well, at the time ascendant materials were useful. The armor core, weapon core, and etheric light can be had for alot less work and time in the 32 and 34 PoE.