After investing a considerable amount of time and effort on the Android 4.0 user interface (UI), Google is taking steps to ensure that it remains a key component of devices.
Going forward, devices running Ice Cream Sandwich with official access to the Android Market will offer the Holo themes as they were initially created. So in other words, developers will have a standard set of UI elements to work with, ultimately resulting in more uniform applications.
This isn't to say that custom skins like HTC's Sense will be going away; In fact, the core aesthetics of those skins will remain integrated into the operating system. But rather than spending time coding elements such as fonts, colors, and margins into an app, developers will be able to pull from either the device's default theme (TouchWiz, Sense, Blur) or Holo.
This move will go a long way to making sure that Android apps look and behave in a similar manner and that devices are updated in a more efficient manner.