Dixie kong should be in brawl for many reasons
1. She is on a game on the virtual council, Sakurai tends to put charecters if there on the virtual council, he always makes refrences to the virtual council
2. She stars in her own game, and is a really fun game.
3. She is popular. One of the favorite charecters in the DKC series, and people where pissed when she wasn't on the DK64.
4.Tiny has become to mature to be in brawl, to down right say it the new tiny is a bit too slutty for nintendo
5. Dixie is a girl, Brawl needs to balance the male: female ratio with there being only 4.5 girls since the previos game (if you consider jigglypuff a girl, and then there is Nana who is half a charecter) so dixie is the next best choice for another female player