1) They can get away with that design wise. Humans are fairly shallow and all of species X would look alike if there weren't glaringly obvious visual pointers, especially from a distance.
2) There are species out there with crazy differences in appearance. Since Charr are cat people, let's look at housecats:
American curl: http://www.petfinder.com/images/breeds/cat/1010.jpg
Siamese: http://chinkisiamese.com/siamese_cats_mkayla.jpg
Munchkin: http://4.bp.blogspot.com/-5TchY3qCe9...chkin-cat7.jpg
Persian: http://www.dogbreedinfo.com/images11...erRedTabby.jpg
All of these domesticated breeds look like you took a cat and went kind of crazy in character creation. With that in mind, there's no reason Charr shouldn't have similar options.