>> It seems that they're no longer using tablet UI, even on Nexus 10

Maybe this is for consistency. I find it a bit of a mental shift when I used the Nexus 7 with the tablet UI. I assume I'd prefer the status on top look & feel on the Nexus 10 as well. I know not everyone prefers status & notification on top, but I'm used to it and I like the consistency of it across phone & tablet.