iMessage is a default messaging service on top of SMS on the iPhone where your messages to a sender appear in blue bubbles as long as the other person has an iPhone (yes, even if you don’t sign into your iCloud). If you message a sender who doesn’t have one, DISASTER occurs--your messages are now in green and you think of the counterpart differently. This stark call out of bad behavior in iMessage is probably one of the one biggest reasons of why people don’t move off of an iPhone. It forces you to think about the pain that the other person might feel when their message goes out in a green bubble should you make the switch away from an iPhone; making iMessage one of the biggest moats that the device has. The blue bubbles of iMessage helps justify owning an iPhone as it’s probably your most used app.
Similarly, I’ve noticed that when an app or a website has a strong set of keyboard shortcuts, it becomes indispensable once you’ve learned these shortcuts. The app becomes navigable without the need of a mouse, which dramatically increases your productivity on there. The #1 feature you use in the app becomes the keyboard shortcuts and the thought of needing to re-learn them on a different app becomes pretty daunting, preventing you from evaluating alternatives. The keyboard shortcuts become a pretty strong reason to keep using the product. Even though it’s not as strong as the iMessage bond on an iPhone, it’s still a pretty powerful one, especially for power users.
For example, Polymail, Gmail, the Adobe suite, Paper, and Slack are good examples of products where I cannot live without the keyboard shortcuts.
If you’re building an app or service, it’s probably a great idea to carve out time to make it accessible via keyboard shortcuts. It’ll impact your churn and keep power users very, very happy.