LOL @ weapon balancing. I can hold 50-odd bullets in reserve for hawkmoon. How's that even remotely balanced? And yes, perks do matter more, but I think Bungie's attitude towards elemental primaries is because no one wanted to use anything other than VoG gear for primaries. BUT, I firmly believe that even if Fatebringer and VoC came without an elemental burn, people would still keep them as their preferred primaries, because as you said, PERKS matter more (and they always have).
You just need to look at the current state of things. Majority of people are either using Hung Jury or another scout rifle with Hung Jury like perks in PVE. HOW does that encourage "loadout diversity"? If you want loadout diversity, create more perks that work well in unison with each other, instead of useless stuff like Exhumed and Danger Close.
If Bungie really wanted people to have diverse loadouts, they'd loosen their grip on Weapon Parts and Strange Coins and make infusion less lossy (especially for exotics), on top of making Exotic Shards available for purchase again.
Here's the way I see it:
Bungie has 3 weapon tiers in the game:
Primary, where ammo is in abundance
Special, where ammo is more scarce
Heavy, where ammo is very rare
In PvP, elements don't mean anything.
In PvE however, they use elemental shields to make their enemies more difficult to kill. And part of the reason they're more difficult to kill is because your weapons with elements - specials and heavies - have less ammo. So your primary is good for unshielded enemies and trash mobs, but that Wizard needs a Fusion Rifle or Machine Gun, which you can't have out all the time.
That dynamic is cool.
Fatebringer and other elemental primaries broke that dynamic by giving you a weapon that could strip through shields AND had an abundance of ammo.
Everyone should understand this. Before Fatebringer's range was nerfed, there was no reason to use anything other than Fatebringer. Having such an obvious choice like that ain't cool.
But the element isn't the problem. When you take away Fatebringer's element, it's still a perfect Hand Cannon. Its base stats were ridiculous (it used to have 13 rounds for the new folks) and it had Outlaw and Firefly. That's god tier shit. When you take away Vision of Confluence's element, it's still a perfectly stable Scout Rifle and it was actually the meta weapon in Crucible after Autos were nerfed. Black Hammer - perfect Sniper. Gjallarhorn - perfect Rocket Launcher.
See a pattern?
All of these weapons were perfect and then putting an element on top made them OP by giving players an obvious choice. A weapon with no tradeoffs is an obvious choice.
An element on a weapon alone however does not make it OP or an obvious choice. Six Dreg Pride is a trash Hand Cannon that barely does anything in PvE, but when I had a Void one drop from Skolas it was my go to PvE Primary for a while. Take away its element and I don't want anything to do with it, but when I heard Skolas was passing out some elemental stuff I checked myself in to see what was up.
Why?
Because I'm playing end-game content to get a weapon - one I can not find anywhere else in the game - to offset that dynamic.
After all that effort, I expect to get some swiggity swooty loot. I want to shoot cool shit, because up to that point, I've been doing the vertical climb with guns that mostly behave the same from one another with slight variations in how well their perks compliment one another. Once I hit that horizontal climb of replaying the same content over and over (and over and over), I want to use a weapon that makes me play differently than how I'd been playing up to that point. For example, instead of only having two weapons to deal with the tough guys, now I have three. I conquered the end-game and now i'm a BAMF looking for more cool shit to shoot.
And that's part of the problem - there weren't really
more. There were barely any elemental primaries, and of that pool most of them were garbage. The good ones however were perfect, and that's because of their stats combined with the element. When there is gold among coal, people will go to the gold.
The solution - I think Six Dreg Pride says it all. Don't discontinue elemental primaries, but rather stop making weapons with no tradeoffs (and also, stop giving them low drop rates; i'm not chasing after a doorstopper). Anything that has an element should have a significant tradeoff to balance it out, therefore preventing it from being an obvious choice. Would I run the Raid if that shitty Hand Cannon had Solar damage? Bet your ass I would, but would I use that gun 99% of the time? Hell naw.