Compliments are awesome. It's basically telling someone else that they did a good job.
A compliment is almost like a form of currency, the more compliments you collect, the more you feel accepted. And for some reason, it almost appears as if some people don't realize that a compliment is absolutely free. Humans are social creatures. We enjoy the happiness of other humans. If you compliment someone else, they'll be happy and in turn you'll also be. That's like infinite happiness.
And another hidden benefit is that it's almost impossible to hate a person who just wholeheartedly complimented you. Imagine telling the school bully, "WOW those are some awesome shoes!". There's no way in hell that he would bully you directly after and he might even put you on his mental list of nice people.
This same principle can be used in a work environment. If you're that super nice guy that goes around spreading positivity, as long as you're half decent at your job, you stand a high chance of being promoted. This is especially the case if you are very friendly with the higher ups. Even if they know exactly why you're being nice, humans still can't help but enjoy a compliment.