I'm with the "make it fit" school of thought. A russian wrestler told my grappling coach I was "too long and skinny for grappler" but changed his tune after watching me dominate a larger, stronger, shorter student that had the "proper" build. If you aren't "built" for something it just means that when you get into it you'll have a method different from the wee people through the same system. Same goes for karate, tai chi, etc.
Hell, boxing, the most rigid sport system out there, every body type is seen in the pro ranks, all do it "their own way" and its still boxing. Watch Tyson then watch Tommy Hearns, then watch Pernell Whitaker...
My instructor tells his students "All music is composed of a handful of notes, just like all martial arts are just rearrangements and applications of the same handful of principles."
and I cunningly added in conversation the other day "The sound of the music is determined by the instrument that plays it."