Why No Time?
Semantics matter, and <time> is just one example of great HTML5 semantics. Something that has context, and is easily distinguishable for us humans.
<data> is too vague, too bland, it sucks.
Site seems down at the moment, but is available via Google cache.
Update: And now, the W3C chairs have requested a revert, on what seems to be technical (parliamentary?) grounds. Seems like a stay of execution, or at least a reprieve. (via Hacker News, where the haters are hatin’.)