I don’t care very much for character portraits — I already know what those characters look like, I have them pictured in my mind, and I prefer to fill in any blanks in their description myself.
Which is a bit odd because I love seeing fanart for games I like and comparing the artist’s impression of the character to mine, but when the art is in the game itself, I don’t know… It feels like that’s the author giving us a “canon” version of what the character should look like.
Maps are sorta “meh” for me. I never pay them any attention (as a child it puzzled me that so many fantasy books had maps, I just couldn’t see what the point was), but their presence doesn’t necessarily bother me either.
I would definitely say that you shouldn’t be relying on images to convey information that’s not in the text itself, though: a great thing about these games is that they’re so accessible for people using screen readers, and we should keep it that way.