Okay, let me rephrase that, you can obtain THE BEST 331 weapons and that is from purchasing the DLC, allowing you to beat Crota and acquire the best legendary weapons in the game at the moment.
V.O.G is not pointless, nor will it ever be as long as they continue to hold the materials to the vanguard upgrades.
In order to upgrade your legendary weapons/rarmor from the Vanguard, YOU NEED ASCENDANT SHARDS AND ENERGY. So many players still run the V.O.G for fun, to obtain the Vex and other wagons, or to obtain the materials to upgrade their new weapons.
This is an expansion, and you only move on. Within two months, everything you have worked for in Crota's End will be pointless, and you will have to run the new raid to obtain better armor and weapons, and you will buy new Vanguard gear, and IF they do stick to the original ascendant materials, people will STILL be running the Vault of Glass for it.
Once YOU get your Mythoclast you will be done, but so many raiders haven't obtained the weapon they want or enough materials to upgrade their new armor/weapons.