I'm don't think I'm understanding, but Paper Mario, and Mario are from two different universe, but they're the same individual in their respective universes, so they're not going to suddenly be female. Link however can because he isn't the same individual every time.
Link is similar to DK in...
I forgot about Spirit Tracks.
That is true, game play wise that is one of Link's signature traits.
Now about the tunic, I'm thinking it's just his starting outfit, but we'll just have to wait and see.
I don't consider it fixing something that isn't broken, just giving it an addition just for...
The word "hero" can apply to both men and women. Now of course Goddess can only apply to females. Honestly if they gave an option for a male, or female Link I'd stick with playing as male Link myself since that's the norm for me, but having the option is a great idea. No where does it say Link...
Could you imagine if that became a thing in movies?
"If you'd like to watch Iron man go to theater A, if you want to watch Iron woman go to theater B." The movies are exactly the same just the main character is a different sex.