He is not as popular as, say, Mai, so the dev team can go experimental on him with no public backslash (I'm looking at you XIII)
I think Mai is just popular when it comes to character desing, not gameplay wise *runs away*
Mai is sure popular, as she is SNK/KOF/Fatal Fury poster girl. You only have to see which characters are used for spin offs or guest cameos in other games: Kyo, Mai, Iori and Terry most of times. The problem is that she is always low-mid so she is not really loved in competitive scene. Also some people seems to hate her because they consider she nothing but 2 giant tits. The funny thing is that many of them love Angel and/or B.Jennet. LOL
I think SNK should feel more proud of Mai and give her more competitive tools and make her more dangerous. But it looks like they prefer to take more care of Kula, Yuri and Vice rather than Mai in gameplay, and that's really sad and why I hate Kula, Yuri and Vice xD
Anyway. I like how Hein looks! :D All his moves are chess pieces LOL