Greetings and Farewells

Hello. Goodbye. These are words that we use everday to initiate almost every conversation. But we barely notice their existence. In fact, we distort and twist them into gross misinterpretations: hi, hey, bye, ttyl. What is the purpose of these strange distortions? Are we so lazy that we can't be bothered to say an extra syllable or type out a farewell? Goodbye, for instance. Why shorten it to bye? It suggests that the goodbye is infact, not good. It seems rude and creates a totally different meaning. Also, why is hi short for hello? It seems to share no meaning but rather convolutes the English language with multiple words that have the same meaning. It's a shame we can't be content with one way to say something and have to confuse both foreigners and ourselves even further.