From the sound of it, the matchmaking is only one problem. What both Brad and Jeff both seemed to have issues with is the lack of context to help motivate them through the grind. Jeff's biggest argument is that he can put in minimum effort to see the content most easily available, quit, and Bungie will reliably give him a way to see the content he wasn't able to see by instantly leveling him with new gear in the newest expansion. Why bother grinding at that point?
Brad's focuses more on the philosophical why. Why should he continue to grind for gear? He goes through a raid, gets nothing, and then has to wait to continue to grind for that missing gear. Meanwhile, the game offers him no other reason to do so other than the fact that he'll eventually grab some shiny new loot.
Sure, matchmaking seems important but how does it help the game feel less hollow?
Here's the thing: I don't get why this is a big deal. Brad and Jeff don't want to play Destiny every day. So what? Destiny has the hooks for some people to enjoy returning to the game every day, and others aren't going to be interested. Is that really such a big deal? I really appreciate that Destiny is a game that you can either play short term or long term, personally, and I've flipped between both since its release in September - playing it daily for weeks or months, or just occasionally. I've really enjoyed the game both ways.
If you're not interested in the drip-feed of loot and levelling I think it's really nice that you can jump in at the major release points, level up, experience and enjoy some of the game's better content and then move on.