We need symbols. We might have progressed through alphabets to cultured forms of languages, but the internet age has brought us right back to where we started off as cave dwellers. Complete or incomplete sentences are fine, but sometimes nothing expresses an emotion better than an emoticon or a symbol.
There are lots of online places which do not support graphic symbols or picture emoticons. Facebook is a prime example. But that shouldn’t keep you away from communicating more warmheartedly.