Texting is hard work. Wait…really? Texting is hard, due to the medium being entirely text-based (hence the name), and it is often difficult to express feelings in messaging.
In the physical world, using your voice and body language are fast and easy ways to express things such as sarcasm, shame, envy or love. These non-verbals are also good for simpler, yet harder to express concepts, like those strange body noises your significant other makes when he thinks nobody is around.