A year or so Ago I would have agreed as this was required at Rogue Trader Tournaments and Grand Tournaments. Back then though you also had the 'Ard Boyz series as well as the Skull of Thrones. There was something to work towards as far as getting into the competitive scene and going to Skull of Thrones or winning the 'Ard Boyz. Then Games Workshop last year stated there would be no more tournament support.
I think at that point the social contract that GW had with their players was broken in a way that frees Tournament Organizers and Players from the requirement of using Games Workshops models exclusively. Other game companies such as Privateer Press, Battlefront Games, and even Catalyst Game Labs have limitations on what models can be used and on modifications. Those companies also give something back to the players. There is prize support for the players and for the games. There is something in it for you to run their products at their events.
I know that it is likely impossible to throw off the yoke of Games Workshop in tournaments and Grand Tournaments. I hope though that Tournament Organizers might embrace the ability of players to use third party miniatures in their armies. There are a lot of good third party miniature companies out there now such as Dreamforge Games who produce beautifully detailed models that fit easily into the universe at a better price point then the models out there by Games Workshop.
Until next time,
-CJ