This reminds me of an opinion that I have which I've been looking for an opportunity to flesh out and share. Despite all of the research and engineering that's gone into the user interface (and "experience") of smartphones, text messaging as an interface has one massive advantage: the perceived cost of sending a text is miniscule in comparison to other operations. I don't have units, but it's probably an order of mag…
My perception of the cost of text messaging for something which requires a dialogue on a portable device is unnecessarily high, compared to a less than 1 minute phone call. This isn't just due to the slowness of typing vs voice.
All of the examples of this service are conversational. Conversational idea description through text messages is generally slower and more ambiguous than through voice.
When trying to get our thoughts communicated into somebody else's thoughts, we need feedback to let us estimate how close the other person's thoughts match ours, before pulling the trigger on a transaction. In text, the packetization of messages delays all opportunities for feedback, and has a more limited bandwidth of expression compared to vocal inflection and body language.
For sending simple status notifications to others, text works great. For unambiguous, unidirectional communication, text works great. When time spent communicating doesn't matter, bidirectional texting is fine. For dialogues where you describe something you want done, text sucks.