Let me preface this with the statement "If it ain't broke don't fix it."
Also INB4 someone goes TLDR, don't respond if you don't read the whole thing. It's rude.
There is no doubt that the Vigilance Wing and Graviton Lance exotic "pulse rifles" are currently the best/most viable/current meta weapons in Destiny 2. Both perform extremely well, have optimized kill times, and benefit a less than skilled hand quite a bit. Both have been available since release, but why only now do we see such a dramatic increase in usage? Because of buffs.
Now I like buffs, they always [spoiler]sometimes[/spoiler] mean a gun/guns are seeing some improvement and will be more viable in the future. Nerf has a negative connotation and though they are sometimes necessary, often have created mass irritation among the community.
When the April update dropped tweaking some weapons, as far as I'm concerned, pulse rifles received a blanket buff and overall all performed a lot better. Vigilance Wing was already the pinnacle pulse rifle and was one if not the only weapon in class that could compete with the overwhelming majority of auto rifle users. The buff only helped it more by allowing the two-burst-kill of guardians with low-mid level resilience. While I am no expert when it comes to stats, I can say with great confidence that such a buff increased the ttk of Vigilance Wing to a ridiculously fast time and rendered many other pulse rifles useless in the process (especially with vigilance wings extremely great perks such as healing and a stable five-shot burst). Graviton was once such pulse rifle that became obsolete.
Vigilance Wing was classified as a pulse rifle but nearly shot two bursts in one trigger pull. It was on the verge of straight overpowered come May and the release of Warmind. Graviton Lance was fortunate enough to receive its own buff to an explosion but also received major changes in the form of a two-shot burst and significantly greater damage. Vigilance Wing was a weapon made for crucible, and though it might have been a bit too good, it fit solidly into the meta game of D2. Graviton Lance got the explosion buff it needed for ad control in PvE, but it wasn't really a PvP weapon to begin with. Now both of them have godly stats and perks that made them unbeatable by anything but damn-near-perfect aim.
Vigilance Wing was powerful before the buff and required no changes, but got them. Hence my opening statement. Graviton Lance was a high-risk-high-reward weapon that filled a niche and should perform at high levels, but it received a buff granting far more than the weapon needed. They are dominating the crucible and the lack of weapon diversification is hitting me (and probably others) pretty hard. I like the fact that exotics are powerful, but that also means something like another underused exotic (for example the Jade Rabbit) should be competing with VW and GL, not losing a range battle it should clearly be winning to a "pulse rifle."
I have a 1.0 K/D and a 1.6 K/DA.
Take my complaints how you will, but I play at least 50 hours/week and clocked over 2500 hours on D1. I know my stuff. Experience is a far better gauge of knowledge about a game than skill anyway.
If you claim to have that much experience in Destiny, then you would know there is always a meta. No matter what.
You should already know the answer to your own questions/thoughts.