Exactly, it's about balance and proportion and one way to create that is with what you wear and how you wear it. I don't consider it much different then working out to create more balance and better proportions in your physic.
And it's not just short people that seek balance and proportion, I dress people for a living and I've never seen a body that could wear absolutely any and everything and look good in it. No matter what body type someone has I still have to put things on them that highlights the good, down plays the bad and/or doesn't make their shape look worse then it actually looks, which clothes can do.
It is a personal preference though, for those that don't care they totally have the option not to care and likewise for those who may want to create the opposite effect i.e. make their bodies appear wider or shorter then it actually is they can totally dress in a way that gives off that illusion as well.
Also, the thing about being short is even if a short person has a bangin' body which many petite women out their do because there is less space to work with it's very easy to wear things that make them look wider and stouter then they actually are which hides how nice of a figure they actually have. Most people aren't trying to do that lol, but for anyone who is go for it. (and the same thing goes for all body types just in different ways).