In animation, the answer is typically "yes." Character designers can make any design appear appealing based on the attitude and personality of the character. Even a villain needs some form of appeal, something that communicates who that character is -- else, the audience will be distracted by the design.
If you'd like to study appeal, I'll share some advice and links to blogs online so that you can 'teach yourself' and use the knowledge available on the internet.
Defining "appeal"
As I hint above, appeal is not necessarily "beauty" – it’s a conscious design choice to make different forms and proportions stand out in a character, based on who that character is and what the designer wants the onlooker to feel.
Appeal can take many different forms -- in Disney's Bambi, the designers chose to make the appeal apparent through contrasts; the head is big, compared to a small body. The legs are long, compared to the small body. The eyes are huge, compared to the rest of the head. These contrasts make the proportions 'appealing' to the eye because they give the eye various shapes to look at.
The importance of negative space
In contrast, a design that has the same proportions might not be as interesting to look at or give the eye periods of "rests." The negative space (the places where not a lot of things are going on) in Bambi's design functions as a type of break for the eye. If you give the eye too much "sameness," the eye won't know where to look and you might automatically find the design 'unappealing' without consciously putting a finger on it.
Glen Keane put this concept very simply -- three shapes put right next to each other is not as 'appealing' as three shapes where two of them are closer to each other than they are to the third.
Coming back to Bambi, the designers also chose to make Bambi appealing through round shapes, which connote softness and typically 'cutifies' anything (whether or not it is appropriate to "cutify" in animation is a topic worthy of its own post).
As Bambi grows up, these proportions change. His head is smaller than his body and his legs appear shorter. However, his design is still made of varying, round shapes that make for an appealing design.
Advice on the web
Griz and Norm share a lot of tips about appealing design on their Instagram, Griz & Norm. Here is an example:
Mark Kennedy also has many posts devoted to appeal on his blog, The Temple of the Seven Golden Camels.
I hope you'll find helpful tips on these sites and that my explanation of appeal has made sense to you. Enjoy studying these concepts!
You can read more of my Teach Yourself tips here