With regards to Destiny, I made it to 20 mostly by myself and then just didn't want to play it anymore. I may have been interested in the raid but what I'm not interested in is grinding to level 26 and then not having matchmaking.
I've been playing the crucible sporadically here and there, but it just hasnt hooked me like Halo did although the mechanics might be a little tighter. There's just too many ways you can be instakilled for me.
Oddly enough, playing Destiny got me to resub to WoW after many many years. I feel like I might be up to grinding in Destiny while watching something else on a second monitor, but it requires to much effort. I can mindlessly level in WoW on the other hand.