What Bungie is doing is selling over priced totally optional cosmetic items, rather than carving off large, important parts of the game to sell for excessive costs. The situations share the "over priced" part of that statement, and that is all.
Dude.
The Dark Below, The House of Wolves, The Taken King were all supposed to be in vanilla Destiny. They carved it out for DLC.
About a year before the game released, Bungie's story writer/lead and cinematics director Joe Staten left in the middle of production on Destiny. He had been with the company damn near the beginning. He was extremely passionate about Destiny.
Everything shown about the game up until then and even a little after showed bits and pieces of all of all 3 expansions. Mercury, the Reef Hub, Asteroid belt around Saturn - all looking really complete.
Now why was this? Bungie pulled a "we did the Halo 1 to Halo 2 thing again where we were given a massive budget and were overly ambitious and a year before release we had to come to terms with remaking the entire game from scratch".
They mismanaged their budget, their milestones, they bit off more than they could chew. And I'm damn sure Activision told them "you are not delaying the game any longer, you're already over budget - you must make this fucking thing any way you can to get it out of the door in 09.2014 and get DLC planned to make us our fucking money back".
As a result, the game became a husk of what it was meant to be. The story progression across the planets was broken because they couldn't go to certain locations because they were shelved for DLC. The plot became incoherent, so they got rid of most of the story. And as a result of that Joe Staten couldn't bear to put back the pieces of his now mangled story into a piss poor minimal garbage product that they ended up with so he just fucking up and left.
That's my theory anyways.
Anyone not thinking that all of the DLC content was originally supposed to be in the game and not DLC, go watch videos of Destiny 2-1 year before release. A lot shit looked really finished. They featured art of the Taken and the Darkness Dreadnaught when they first announced the game, and after the game released they removed those images from their website because - oh shit we're showing them stuff we had to axe and are planning to release as DLC not for another year.
Bungie/Activision put out a $60 game that was basically in beta with placeholder assests for items, a shitty progression system that has been majorly reworked 3 times and now a 4th one is coming, an economy with the shittest RNG and a raid that still suffers from experience-ruining-bugs for almost a year. They didn't even let you control in-game music volume until a few months ago for fucks sake.
Then they have a really lackluster DLC 1, and then a kind of ok DLC 2. Minor variations and mechanics added to a stupidly low amount of new missions were expected to garner praise now that they actually made a small effort to not use the same 2 mission scenarios over and over and over.
Destiny has just been content anemic from the start by design. They've been selling us the cleaved incomplete and ill-conceived content for inflated prices. And now they want to do it again.
$20 for fucking emotes?
Get da fuq out of here Bungle.