Iron Banner runs once a month if memory serves me correctly. What good is a pve event going to do? It's basically going to be more bounties with different objectives anyways. This is Destiny as it is and I can't see it getting much better even when how is released. People are constantly wanting this and that and instead Bungie fix a heavy ammo bug and mm in weekly heroics. I doubt either of those two were high on many people's wishlist.