Different situations most likely. Destiny launched as an overhyped game that most felt didn't have enough content to justify itself to begin with. It then went on to release DLC that, for the most part, underwhelmed with the content again (Dark Below is more guilty of this than HoW) despite being pricey for DLC. People feel cheated and now Bungie is releasing a new DLC that's even more expensive, so a lot of people are wary or frustrated. Not to mention Activision have been greedy asshats for years with CoD, which adds fuel to the fire. Zeroes was bad but it was heavily criticised back then and (it seems) like Phantom Pain will more than make up for it content-wise. Ultimately I'm in complete agreement with you; the hate is stupid. But I can kind of understand why people would defend Metal Gear and not Destiny.

Both situations are similar in that you have to pay $130 to get the full destiny game and $100 to get the full metal gear solid game. Yeah the phantom pain looks like a good game and the taken king looks like it has more than enough content to justify the price. GZ was nothing less of a cash grab, but destiny's DLC was made with an effort to improve. That's why TDB had a consisted storyline even if the DLC as a whole was not very good, they were at least trying to improve. They also improved with HoW. Phantom pain was just an easy way to make money off of the hype of the game, similar to how destiny made most of its money off of hype. Neither companies should be defended for those actions. What's bad is that when someone says they're looking forward to TTK they're reminded of the $90 beta before this DLCs release but when someone says they're looking forward to the phantom pain everybody is commenting "yeah me too" or "it's going to be the best game ever", nothing about the GZ demo that people played for. Nobody should get hate for liking a game, and it's especially bad when only one game is called out for something that other games have done.

See, this is where I think we end up disagreeing. You don't need Ground Zeroes to get the full experience of MGSV, it's little more than a prologue. Destiny however, given it's nature, almost requires you to buy the DLC if you want to keep playing. You can skip Zeroes and not miss a beat. You can't say the same for TDB, HoW or TTK. But again I don't think they're all that comparable. One focuses on single player, the other on multiplayer. Destiny releasing DLC isn't a bad thing because they need to keep things fresh, but I think we can both agree that some people don't like having to keep putting money into a game to keep it enjoyable, especially if those people aren't familiar with subscription based MMOs.