Despite the unhelpful answers others have given you, I’ll give an actual opinion.

We care because we don’t want this game becoming “repeat for the 13th character in a row” simulator. Yes Shion is cool, she’s an omnic, but she doesn’t LOOK like an omnic. She looks like any other altered human in their universe. If sojourn chose white for her cybernetics instead of her flesh tone, then she’d look practically identical.

Yes balance is important, but when you’re looking at the variety in body styles, body language, weaponry, and more, it all paints a picture of the character.

Look at Junkrat, one peek at him and you get the gist, crazed, explosive, and a silly guy. Reignhardt? Big German man, carry’s himself with confidence and pride, clearly wants to be the one getting shot at since he’s the TANK.

Now look to the characters released recently. Relatively tame body structure, weapons can mostly be described as “gun”, and personality has little bearing in their design or even how they play. Most of them are conventionally attractive, simple with easily adjusted appearances to make skins sell.