I am pretty sure it is just that there are a lot more hunters out there. As a hunter I break positive "most" of the time. But if you look at a breakdown of my kills 95% of them are pulse rifle kills. And the other is arc blade and blink strike. I suck with grenades so I only use them rarely. Its a really fun class. But it has taught me how to fight other hunters. When I see a golden gun or arc hunter I just back up and jump away while shooting them. Since hunters dont get damage resistance while supered they die just as fast.

I think its mostly because Hunter has really viable supers for PvP, coupled with that most people play hunters. They get a chain-kill super, and a ranged-kill super. Titans have it pretty weak in terms of Supers, and I think Warlock is in the middle of it.