Yeah, I hate that design. I don't care that it's 'classic.' 'Classic' doesn't always mean 'better.'
I like the early KOF design. Like, from '94 and '95.
Because it looked like something a martial artist might wear.
SNK apparently thought so, too. Otherwise, they wouldn't have changed it for KOF. It had to fit the aesthetic of the game's look.
I see you points. Soon in KOF, Athena's image drifted into that of a stage fancy idol, rather than a martial artist. :-)
They played with the original concept that Athena was a 'simple schoolgirl' with Psycho Powers, hence leading to a double life. Thus Asamiya Athena came to portrayed as a music idol making puns on a superhero-like persona in KOF, actually. You see in KOF96 Esaka stage the posters for her tour, etc.
Neverless, as soon as they started using first-up animations, and that's '95 IIRC, Athena was starting throwing away her blue seifuku. That's her basis anyway.
Of course you may not like it, and indeed 'classic' is not necessary the best in anyone personal opinion and preference, yet I just say it's coherent with what they did in KOFXII-XIII as a whole. And coherence is not a matter of personal tastes, but facts.