"Judge me by size, do you? And well you should not - for my ally is The Force.""Luminous beings are we! Not this crude matter!" Master Yoda, Ep V
(That's from memory - I hope it's not too far off.)
One reason why I don't think a Size attribute is a particularly good fit for Star Wars. "A little short for a Stormtrooper" is colour, not an attempt to judge how well Luke will do at actions requiring strength or physique.
(The Wookie's ability to rip arms off is about being a Wookie, not about having 18 STR and a Powerful Build feature.)