You can't have your cake and eat it too. You can't design a game with interesting and fair mechanics to fight AI with, and then carry those exact same mechanics over to fight other players.
This is why you never give players abilities that stall encounters or reward them extra health. It's destined to contradict one another and ultimately fail at a fundamental level, unless - and only unless - the game's gunskill ceiling is really high. Higher gunskill allows PvE to dictate PvP balance (and not the other way around) because the gunplay will matter more than the ability sandbox.
So for example, if the developers didn't like the way an ability or weapon archetype was behaving in PvE (like the Thorn), they could buff or nerf it. Assuming they didn't completely redesign it to make it simply "more powerful", its effect on the meta would be marginal because the game would still be balanced around moving and shooting, and not stats and abilities.
Unfortunately, Destiny's gunskill ceiling is one of the lowest out there thanks to ADS and mindboggling mid air penalties. Therefore, the deciding factor is almost always who has the better grenades, the better armor and the better weapon perks.