Let’s start with a sentence. “I think that’s really great.” Punctuation, traditionally, has been what changes the intended tone of the sentence. “I think that’s really great!” I think that’s really great?” “I think that’s really great…”
Let’s change to a different sentence for the next example, because “great” has stopped looking like a word. “Jane told John she wasn’t coming.” There, basic, boring sentence. With punctuation, respectively: “Jane told John she wasn’t coming!” “Jane told John she wasn’t coming?” “Jane told John she wasn’t coming…”. Here’s where emoticons enter the picture. “Jane told John she wasn’t coming :)” “Jane told John she wasn’t coming :(” “Jane told John she wasn’t coming ;)” “Jane told John she wasn’t coming >:(” “Jane told John she wasn’t coming o_o”
Punctuation is meant to convey tone. Emoticons are meant to convey body language, as a symbolic representation of the other person’s expression, because otherwise there are a whole mess of misunderstandings. Normally, you can’t convey sarcasm through plain text, or joy, or sadness, except through explicitly stating it, and it hinders communication. Look at the example sentence above. There is a completely different context to each sentence provided by the emoticons.
There are other tools than punctuation and emoticons to distinguish tone in text. Italics, to emphasize, and bold, to make your words stand out. IF YOU PUT YOUR WORDS IN ALL CAPS YOU LOOK LIKE YOU’RE SHOUTING. ifyouremovethespacesitlookslikeyou’remumbling. When you surround key words by asterisks, it looks *really* sarcastic. Describing actions surrounded by asterisks conveys the impression that this is what you were doing when you wrote these words. *smirk* *shrug*. Drawing out the letters of words makes it souuuuund like you’re whiiiiiining.
I honestly just find it fascinating how many ways we’ve created to express ourselves in a world where most of the expressing done is in text, online.