From the article:
If someone steals your card, they won’t be able to use it without your code unlocking the number and coding the strip. Since the credit card number is generated fresh for each transaction, there is no data to be stolen in the case of a hack. Citibank is now using the cards in small pilot programs, and the company is hoping to see more banks and cities using the technology.
The dynamic nature of the magnetic strip opens up a number of other applications. I saw a card that had two numbers, so you can keep your business and personal accounts on the same card. You hit a flat button next to each number to select it; a light shines showing you which account is active, and the magnetic strip is coded with that number. Change accounts, and the magnetic strip is instantly reprogrammed. Each card comes with a battery that should last three years.
Of course, this technology is being developed because the US has been so bloody slow adopting the Chip + PIN system that most other nations are adopting. While there are certainly problems with Chip + PIN it makes a lot more sense to work on, and try to resolve, those problems instead of inventing convoluted new technologies to address known-bad systems. Curious about the payment card fiascos? Check out the comments of the Ars article, you might learn a lot.