I mean, seriously?

Code html:
<header>
</header>
 
<div class="header">
</div>

Now don't get me wrong, I find the new semantic tags pretty nifty, but I'm not convinced the overhead of an htmlshim is worth it. Especially since older browser usually means older computer, which means unresponsive, slow, buggy mess of a site if you put too much javascript into it.

The tags all fall squarely into 'nice to have', as opposed to 'necessary' territory.

Or maybe I've become a grognard.