I like very little death metal, and in fact what little I do like isn't really true death metal. But I'm not about to start another genre debate...
Mainly posting to say it does take talent, in some cases anyway. It's not easy to play incredibly fast and it takes a lot of strength to do it for that long. So there is musical talent, to a degree, but no you wouldn't use a death metal band as examples of a high level of musicianship and musicality.
On the other hand, it's all a matter of opinion. I personally hate Jimmy Eat World, which you have a quote of in your sig. I'd laugh at you if you tried to tell me they were good musicians. It's all opinion. And then there's the large fact that the majority of people don't listen to pop, metal, hip-hop, punk or any sub genre of those or any sub genre of those sub genres for it's musical quality. People listen to that group, which I often just refer to simply as Mainstream, just to be entertained. A lot of people don't mind the predictable chord progressions and mediocre singing. They just want a tune they can whistle.
tl;dr Yeah, death metal isn't that great.