Except that matches in the real world will not play out like in that mostly staged demo.
In reality you are going to see a ton of one shot body shot Speer shit.
There are numerous ways to play and shotguns are just one viable method. I typically run scout rifle, shotgun, and rocket launcher as that is what I am most effective with. Some dominate with hand cannons like Thorn, but I hate hand cannons personally so I leave that to others. I have no problem with being killed by another strategy. Just makes me revise my own.
I love how varied Destiny PvP is. There are a lot of techniques being used and different abilities coming into play.
I guess I just see it differently, but I have never understood why some dislike PvP modes in general. I really enjoy facing opponents that are not programmed to act in a certain manner. Much more thrilling to take something out that is trying to out think you.