Don't act like I'm one to mention I am proud of our society, because I'm not. People these days has used hip language like "What's up" And since it has been around for quite sometime the people have assumed the word into the word "hi".
nearly all languages have small,common phrases that are used for stand ins for the formal words that have been designated as greetings. at different times it's different phrases. that doesn't mean "hello" is unuseable. these are only variations that mean the same thing. it'll pass.