I think Rainbow Dash deserves to be a Princess!!! Princess of the Sky, Princess of the Pegasi, Princess of Rainbows, but most of all, the Princess of Loyalty <3 She's got the talent and the skills to be a Princess. Celestia said that Twilight deserved that because she showed generosity, optimism, devotion, honesty, kindness, and the leadership of a true Princess. But I think at some point or another in the show, Rainbow showed those qualities as well. She's special, her and the rest of the elements too, Twilight shouldn't be getting all the special treatment /: Sorry, now I know I'm ranting XD
This is a really interesting take on rainbow dash. I always wondered if Lauren Faust thought at some point about making the different races of ponies physically different to enhance their different natures.
This is very much in line with what I would imagine a more stylized pegasus race to look like; a much more aquiline form to reduce wind resistance, and a sleek, trim structure to reduce weight. A really nice concept!