For myself, its probably a mix of a few major factors. The big things being that builds/abilities overshadow the gunplay element. Support abilties(i.e don't win the fight by themselves) are shifting the fundamentals of crucible away from what it is at the core, a movement-based shooter. This isn't something I think a substantial portion of people who enjoy PvP will take to because its less about the FPS element and more about the rpg element like the build crafting. Further, the sandbox is moving away from what I think balance is. Though usage rates have been up for some weapons the way this was done makes no sense in my head. The guns that are higher RoF, meaning more forgiving, are the guns with the better off ttks and playability (like AE stat) which is unjustifiable in my head. The outliers weapons are allowed to represent entire archetypes for some cases like chaperone for slugs and main ingredient for fusion rifles which skews those usage rates too. Finally, I think the gun economy is just reaching its peak where you can't make guns better anymore without knowingly inducing power creep through creating/refining perks beyond the current sandbox