The top priority for the next Android update, codenamed Gingerbread, reportedly is to homogenize the user experience and address criticisms of fragmentation. This could severely curtail the freedom of licensees to create their own user interface overlays, most famously, Motorola's Motoblur and HTC's Sense.
It's probably a toss up at this point which approach is better. Apple has proven that absolute uniformity of experience is no barrier to wild acceptance. On the other hand, a uniform approach to user interface will tend to dampen the pace of innovation to a degree.
Google does have a big stake in preventing Android fragmentation, which makes it much harder for developers to create applications guaranteed to run on any Android device with a specific version of the operating system. On the other hand, the HTC "Sense" user interface is quite a differentiator, so handset suppliers might not like the restrictions on their freedom of movement.
As with all engineering decisions, there will be trade offs. A uniform UI is better for software developers, but arguably worse for hardware developers. Most consumers seem to indicate by their buying preferences that a standard UI is, if not a "good" thing, then at least no barrier.
In the battle between "open" and "closed" approaches to development, "closed" seems to be getting more traction these days.
In the battle between "open" and "closed" approaches to development, "closed" seems to be getting more traction these days.