Okay, so I've decided to point out why I have my point of view on the loot system in Destiny. Why I feel it's terrible, and point out that it does in fact exist since apparently it doesn't? lol
A progression based system would be fine, but Destiny's items aren't designed like that. In a typical MMO, a specific item is always the same. A Berserker's light armor exotic chest piece in GW2 will be equivalent to another. A Bonetti's Rapier will be equivalent to any other Bonetti's Rapier, minus the sigils you may swap out.
This is not the case in Destiny. Exotic weapons are equivalent, but that is all. Legendary weapons and armor(and also exotic armor) are not, not even copies of the exact same base item. Storebought legendaries are the only ones that remain static, and those tend to actually be mediocre versions.
You can obtain 100 copies of The Devil You Know from drops etc, and every single one will likely be different. You could actually probably acquire THOUSANDS of copies of that weapon and have them all be different. Many will be better than the one you can buy due to having better mods. This design means there is, in fact, a loot system in this game. This is just like Diablo etc, you want to get a good version of the weapon or armor.
Hitting level 30 is cool. But guess what? Odds are the armor you're wearing to hit 30 is also not BiS. A piece of armor has the following variables when it's rolled:
1. Stat combination. What combination of Int/Discipline/Strength will it have?
2. Stat values. How high are those stats going to be?
3. Other mods. Ammo capacity, reload speed, etc.
You could get a ton of legendary helmets and still not have a perfect one.
The game is designed with a core part of random loot systems in mind. It's just missing the other part. The part where you actually give people those items and let them try to get better ones.
The items bought from vendors serve to provide you with something. They allow you to advance a bit. But you will never, ever, EVER, reach a point where you're completely decked out with BiS purely through bought items. And I'm not just pointing that out because of raid gear being the only way to hit 30. Even if bought legendaries could get you to 30, it wouldn't be possible to hit perfection that way.
Now, getting a full set of perfect items is a pipe dream in any loot game, but it's something you can try and feel like you're making some level of progress toward. "Yes! I got a better Thunderfury!" is something you may feel in Diablo 3. Getting your first Thunderfury was fucking awesome, but getting an even better one is, too! Is that possible in Destiny? Sure. But is the loot system designed to make it seem even remotely likely? Absolutely not.
There are a lot, and I mean a lot of people like myself that would play Destiny for months and months after hitting 30 and whatnot. We would be farming for better stuff. Inching closer to our ideal. The item design supports this. Unfortunately, the distribution does not. This is why I stand by my statement that they took some of the worst parts of various genres and forgot to include the parts that make those acceptable.
I understand there are people that disagree. And hey, it's awesome that there are people that like the game as it is. But all I see with Destiny is a massive amount of potential, even without more content, that's being thrown down the drain. And it's weird, because many of its problems don't require crazy redoing of core game systems. They don't require developing new content. They just require changing some numbers around on drop rates and adding some stuff to drop tables, like strikes.