I'll admit that it isn't the most detailed comparison. But we're talking about iOS "looking" tired. Multi-tasking, wireless sync, background processes etc. really don't have an impact on the way the OS looks.

If they got the springboard right, why change it? For the sake of change?

I think the larger question is "did they get the Springboard right?". I don't think it is exactly the zenith of user experience, especially on a platform like the iPad.