I have seen the other vids. FWIW I don't think it has too much going on with the 3D background. That is more of a polish than a feature IMO. The informatio is still presented the same, just "prettier". Widgets can also have as little or as much in them as the writer cares to provide. I am certain widgets would not be the exact same between the different OSs. I guess I go back to the statement that the things you have listed doesn;t innately make the OS written for tablets and only tablets. Those things should be incredibly easy to alter in a phone version.
Allow me to use an example...
have you seen iOS on an iPhone versus the iPad? The version is the same, many/most of the features are the same, but the iPad version often has more information available at a glance (a good example off the top of my head is the web browser... however I have never owned an iPad so I am going from memory from videos). Since the iPad came out after iPhone, it is simple to think these things were just added in to the iPad version. To be quite frank, this sort of thing can also be thought of as being taken out. You mentioned the 3D UI. While I am by no means convinced that it is too busy for a cell phone version of the OS, if Google decides it is, they can simple remove it and keep the "old" one. I personally do not see that happening though.