Starbucks Mobile Payment: Technology for the sake of being cool?

I read an article on Read Write Web today about the expansion of the Starbucks mobile payment program. The program was launched as an iPhone app in September 2009 to Starbucks outlets in Seattle and Bay Area. After expanding the program to over 1,000 outlets in March 2010, Starbucks announced that it would deploy to even more stores across United States.

Here’s a video from September 2009 about using the iPhone app to purchase Starbucks coffee.

The Starbucks iPhone app is actually more than just for payment. It is also a loyalty program where customers can get points (“stars”) with every purchase. The expansion of the program indicates success. But why?

The customer loyalty program makes sense to me. Coffee is addictive and a lot of people drink it out of habit. With so many coffee shops around, it makes sense to have a loyalty program to bring your customers back to you. I almost always sign up for a loyalty program in stores that I frequent, and I would get a Starbucks Card if they offered it in Singapore. 

However, what is the benefit of having a mobile payment program in the iPhone app? In what scenario would you use the mobile payment app in place of cash? Is it when you’re out of money? I think most people will have enough cash in their wallet to pay for a few cups of coffee. If I don’t have $10 in my wallet, I’d be in front of an ATM before I go to a Starbucks. Is the mobile payment app for the times when you forgot to bring your wallet? Even if I have my iPhone with me, the first thing I’d do is go back and get my wallet, not to go to a Starbucks.

I also don’t quite understand the motivation for paying with an iPhone app. You’d have to pull out your iPhone, run the app, press a few buttons and scan the bar code. The video above shows that the process could be a little awkward. It’s definitely less convenient than pulling a few dollar bills out of your wallet.

So, what’s the point of the mobile payment system? This is not a rhetorical question, by the way. I’d really like to know from those who have used the app before.