I don't believe that is true in all cases, and I do understand that lyrics are quite important to a lot of albums (esp. in black metal, etc.).
The Lord Worm issue is my focal point, so I think you should explain why you think you can just assume that Worm's vocals are "lazy" instead of his ideal form of artistic expression. There really is no way to prove that he is meaning to do his fans a disservice by not fully pronouncing all of his lyrics...it might be a Dr. Jerkyll/Mr. Hyde thing (eloquent lyrics with ridiculous, feral delivery) or something...it's interesting to think about, and writing it off as "lazy" is, to put it bluntly, lazy.