Adding to this, I also think people generally have trouble accepting change, wether that is to character or appearance. I do believe that if the situation was reversed, say Bella was the original Ellie and the game came later, people would also complain about the "new" look in the game, simply because it's so different.

The difference here is that Bella is a real person, who reads these hateful comments and gets affected by it. I only wish more people would look past appearance and see the value of talent and skill. They picked Bella for a reason and even with how little we've seen of her, I know they made the right decision and she's doing an incredible job.