Was going to try to get this at the top of the page, but thread is moving so slow that'll be Tuesday before it happens, so here goes.
Light: A Complete Paradigm Shift For Year 2
The new Light system succeeds in many ways, but also creates significant issues for the end game, some of which are objective design problems, others are relating to player psychology.
Goals, as stated by Bungie, for decoupling player level from light and adding more gradation were:
 — Players wouldn’t be punished so severely for missing one weapon/armor piece (#forever29).
 — Players would be more willing to play with others at a lower light
 — Players could feel progress more frequently, as opposed to progression only happening 1–2 per expansion (e.g. level 30,31,32).
I would say that the new light system accomplishes each of these objectives, with varying degrees of success. The system is most successful before reaching level 40 and 290 light. Additionally, combined with the new infusion system, it allows players to use more gear, rather than just the raid gear like in Vanilla and TDB. It’s not as clean as Etheric Light, but it’s there.
However, the pre-endgame progression hides and even creates problems that don’t appear until players hit 290ish light. On every screen, both your character and your gear, Light is the biggest number. It puts into the player that Light is the most important stat. Bungie realized this wasn’t necessarily healthy for the community so your character just shows “40”, not your light, even though light is far more important to determining your damage. Look at the Iron Banner/Trials “Power Matters” charts as evidence of this.
Additionally, during leveling drills home that progression is about getting higher and higher light. And at a ramp that is unsustainable. Now this is is an issue in all loot games, but Destiny’s endgame is balanced in a way that doesn’t mitigate that. What do I mean by that?
Two objectives for the Endgame in Destiny, per Luke Smith:
 — A lessened vertical ramp to allow players to diversify
 — Leaning into the Destiny as a loot game, hence more equipment slots
I would say that both of these aspects are a failure. The ramp to 320 is essentially infinite and drops are neither frequent enough nor do they have meaningful differences enough to allow for enjoyable differentiation. Obviously I could expand on that, but I want to focus on where that leaves us: all sense of progression, both deliberately and accidentally fall on the Light system.
Year Two Light Issues:
- Drops in Year 2 are now RNG on top of RNG. RNG for the slot you want, then RNG for the light you need. As opposed to year 1 where you only needed to get the right slot to drop.
- The Game is balanced around light, not perks, such that perks are often too minor to make a difference in play. This reduces the viability of horizontal progression.
- Additional equipment slots co-opted into light system remove cosmetic options for players.
- Additional equipment slots co-opted into light system have trivial effects at best (XP bonuses or infrequent orb generation from artifacts), but are mostly detrimental (ever find a 320 ghost?)
-  Character level is largely vestigial at this point. Character level doesn’t impact any player traits other than what gear you can use.
- Light further complicates damage calculations. It now involves 5 factors:
 — Your character’s level
 — Your character’s light level
 — Your weapon’s light level
 — Your target’s level
 — Your target’s light level
This makes it very unclear as to what light level of weapon to use. See this comment for more.
-  Additional level caps are introduced instead of just two like in the past (28/30,31/32,33/34, it’s 300/310/320).
-  End game activities are incentivized via Light-based rewards rather than gameplay changing rewards. “Play SRL for a 320 helmet.”
-  Using gear you like or gear better suited for a certain activity can mean going down in light, which may be okay from a damage perspective, but feels bad to the player.
- Gear drops and decrypts at current equipped light, not maximum possible light:
 — Normalized or lower level activities that would actually allow for using lower light gear have gear drop automatically that's low level.
 — Decrypting Exotic engrams, for example while in SRL gear, means getting 290 light gear instead of 310.
 — Gear drops outside of reset and event activities capped at 300, but much more commonly ~280 light. Meaning that to use your new gear will cost you in terms of higher level drops.
- The Vault is too small to hold infusion fuel needed to efficiently level up a new good drop.
- Infusion aside, the light system actually makes the pool of usable gear smaller. Because instead of having all gear drop at the same level, gear drops much lower than would be valuable to a player at end game, and there isn't a consistent, painless way to bring everything up.
-  Limits activities for end-game players because only a tiny fraction of activities provide progress potential.
 — Nightfall only gives lower level legendaries
 — No reason to do normal mode raid
 — All other activities lack meaningful difficulty selection with equivalently meaningful loot
-  The loot system doesn’t provide drops to satisfy the Light needs for all slots equally. (e.g. no ghost / artifact engram).
-  The Raid reward system was changed from powerful gear to higher light gear, which isn’t near as enjoyable to use or chase compared to Fatebringer, Vision, etc.
In summary:
 — Progression in Year 1 was about Gear that Increased Your Level and Weapons That Changed How You Played
 —  Progression in Year 2 is entirely about Light Level, and at significant cost.
But I haven't even mentioned the biggest problem with making Light the focus.
The Biggest Problem:
Light progression does not fundamentally change how you play the game.
Being a 310 vs 311 doesn’t feel any different. Using a 308 Smite vs a 314 Smite is no different. But the balance of the game, the loot systems, the events, the character screen, etc. are all focused on getting that number up.
Year one we were chasing interesting weapons and cool looking armor.
Rewards that changed how we played. Year Two is about chasing the number on your name plate.
This is why Year Two feels bad even if it’s superficially better.