I understand what you mean. If it's a cartoon why should I copy reality, right?
But there are basic characteristics that I draw the line on. If I'm going to animate a seal or a dog, I'm going to know learn how they move. Just cause it's a cartoon, in my opinion, doesn't mean I should make the dog move like a seal. Unless it's for comedy, it simply won't make sense and you won't be pushing yourself to be your best.
I mean, naruto is a manga, not reality, right? But you'd probably find it looks a lot better drawn than other really anime-ish mangas.
It's because masashi put more effort in making the drawings as realistic as possible while keeping his manga feel than other artists.
That's why you'd feel the anatomy in naruto is more 'correct' than in other mangas, that's why it's easier on the eyes, and that's why it's better overall, in my opinion.
When you mimic the details of reality instead of cartoons, you're stepping up from copying a person's imitation of reality to making the best possible art you could have made.