I have to agree with Eris here. I like 40k more than just about any other table top game out there right now. Having said that, I don't know too many of them, but I know a few, enough to make a choice which game I play. One thing that I really love about 40k is the models. That matters a lot to me, (gameplay as well, but models too). I can't play a game with models that aren't... special.
Now, GW does put out really high quality models, and does put out amazing looking units, but sometimes, majority of the time Forge World models, they turned up warped, cracked, and improperly made. I have had friends who have bought titans, and have been disappointed with the quality of the model. This cannot happen. If you spend 600$ on a model, it CANNOT be anything short of PERFECT.
Now, does it hurt the 40k economy and community.. maybe. It depends. It can really go either way, because the community will be there as long as there is a desire to play, and as long as GW puts out new codices, minis, and can grab new players.
But with Forge World, if they cannot put out PERFECT models (with a few exceptions of course.. an accidental 'bad' model with flaws, that is REPLACED FOR FREE) then they do not deserve the business. We only allow them to do so because there is nobody else that puts out quality like they do... until now...