This slight interface change comes for a good reason: one of the main new features of the app is downloadable content. As you can see in the photo of the upcoming app update, the app will promote content from the three Apple content stores. This content normally costs money, but it will be available free for a limited time via this new app.
Apple is looking to boost content sales with the new app and also hardware sales. When a new iOS device is sold, retail store employees will reportedly offer to install the Apple Store app on the newly purchased device. Only 20% of customers are aware the app even exists so this should boost its popularity.