For a lot of people, a cup of Starbucks also feels like a "must-have". We all feel groggy in the morning, and spending $4 for coffee isn't a lot if it helps us survive the day.

An app on the other hand, most of the time doesn't give us that same feeling. It's more of a nice-to-have, or nice to play with once and then forget. If it's an utility you use everyday like Evernote, it's different of course.