A compliment, noun, is "an expression of praise, commendation or admiration". Things like, "you're so hot," "your eyes are very pretty" and "your hair is totally rad" are all considered compliments. Other things that are considered compliments include "you have great taste in music," "I love that you ride horses" and "you're so honest." Don't get me wrong, it feels amazing to be complimented on physical appearance, but we shouldn't want a friendship or relationship based on our physical attributes. Things like our hair, body and faces change all the time (google: "Daniel Radcliffe puberty," "Natalie Portman puberty" and "Keith Richards then and now").
A relationship based on appearance will not last, because the appearance of a person will not last. Our bodies are constantly changing. Things like the music someone listens to, the things someone does when they're happy and someone's favorite movie to watch at midnight when they're alone all say more about someone than the curls of their hair, the sharpness of their jaw line and their complexion. I'm not saying we should stop entirely with complimenting on physical attributes because these compliments feel great; I'm saying we should focus on the more permanent qualities of our friends and partners.
This requires a little work from both sides. These types of compliments require that people are open and honest with each other. These compliments require that we know what we are looking for in each other and not on each other. They require that we are comfortable with who we are and what we like. They require that we don't doubt ourselves or each other.
Knowing what we want in someone requires a lot more work. In order to decide what traits you like about someone, you must know what you like. Do you like listening to music loudly? Do you like driving long distances? Have you ever thought about having kids? Knowing the answers to many personal questions will help you connect to someone who is equally as open. Once you decide what makes you happy and who you are, you can decide what traits in another person best complement you.
To complement, verb, is "to add to (something) in a way that enhances or improves it; make perfect". Complementing another person makes a perfect whole. A perfect whole usually means a perfect relationship. A perfect relationship built on complements will last longer, because they will not differ like our appearance will. This goes to more than just our boyfriends/girlfriends and partners. Our relationship with work must complement us. Our relationship to our free time must complement us.
Why are we complimenting others on the attributes that don't complement us?
