Destiny charges way too much for its expansions. I'd be fine with the price if there was enough of the main game to make it worth the commitment, but I exhausted everything except the Vault of Glass pretty quickly, and I couldn't ever find enough people to even try the raid, thanks to the lack of matchmaking. But you play all the way through Destiny and then months pass and you buy other games and play those and then Destiny offers you a whole new raid for the price of a decent game on Steam. Maybe I'm embittered by my difficulties with playing the raids, but that's not an appealing prospect. House of Wolves was more attractive, but expensive, and I honestly don't think it's worth it.
I think what Destiny needs is a little more free content. A new strike or story mission every so often to keep people interested. That's how MMOs tend to do it - outside of major expansions, updates add new things for free, but Destiny's idea of 'updated content' is 'Queen's Bounty missions.' Yep, that's right folks, we'll keep you interested by cycling some arbitrary objectives every weekend.
I'm a level 28 Warlock. I own Red Death, four exotic weapon bounties, three of the Awoken Queen's sniper rifles (one for each element) and lots of exotic armour pieces. I loved Destiny while it was fresh and new but I don't love that I'm expected to replay the same content over and over again with no variation until I pay, in total so far, the price of a whole new game just for a couple of extra raids.
And just to take the piss, PlayStation players get an exclusive strike? In what universe is that okay? Can't offer any strikes for free or any other new content, but you can do exclusives?