Does it matter? Do you think everyone who buys CoD or battlefield plays multiplayer? A large portion actually don't. Yet there are other groups of people who buy them strictly for multiplayer. Plus, you'll also notice that, with the exception of swords, the exotics that require PvP steps are actually best used IN PvP. They're not good PvE weapons. So if you don't like PvP, why would you even want them? The answer is to have them all. So, again, logic only serves right that if you want everything in the game, you'd have to play everything in the game.