Because it's boring. And no browser implements it. You're not doing anybody any favors by implementing it. That google rich data thing? It's done with html classes too, that works equally well, and we've had them for a while now.<p>Seriously, I like microdata, I think it's useful, but this kind of utopian, far-away 'we should use this because it might be better in the future' never got us anywhere. <i>That</i> is the lesson we should learn from XHTML2, not 'adding more attributes is cool'.
Until recently, one of the biggest publishers of such microdata (in its earlier incarnation, microformats) was Upcoming.org, an events startup acquired by Yahoo.<p>Gordon Luk, the lead engineer, wrote an excellent post describing his frustrations with microformats:<p><pre><code> [...] my experience with being a microformat publisher
has shown that things are exponentially more complex
than they let on in the “sales pitch.”
</code></pre>
-- <a href="http://getluky.net/2009/01/08/a-warning-about-the-real-cost-of-microformats/" rel="nofollow">http://getluky.net/2009/01/08/a-warning-about-the-real-cost-...</a><p>HTML5 Microdata seems slightly more rigorous and abstract, but still, commingling presentational HTML with an informal data API is just asking for trouble.
The real reason for this, IMHO, is one of the last points of the article - No major browser has embraced it as a core feature. Getting this into say Mozilla or Safari would go a long way to make it standardized.<p>Also, I'm waiting for a usable "Receipt" microdata - imagine buying something, then when you get to the receipt page, it gives all the information about the transaction, ready to go into your financial management software, or into a program to keep track of the packages being shipped to you.<p>Then again, this may be because I hate Intuit with a passion...
I've used <a href="http://microformats.org/" rel="nofollow">http://microformats.org/</a> in the past for marking up dates, addresses and the like.<p>Looking at the examples on the Google page (<a href="http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=185417" rel="nofollow">http://www.google.com/support/webmasters/bin/answer.py?hl=en...</a>) of marking-up breadcrumb links though there is a clear step away from clean functional markup. It looks like the sort of code people make (have made) to add styles to containers and what not. Couldn't semantic info be simply added in any tag available thus:<p><a href="/a.htm" typeof="breadcrumb1">a</><a href="/b.htm" typeof="breadcrumb1">b</> ...<p>Why would that be so hard?<p>Perhaps further detail could be added by having a typeof-sheet that references the id of a node and details the information it presents (like external CSS).
Arbitrary semantic data on the web at large is DOA, just like the semantic web.<p>If you think about it, a big part of the appeal of facebook is that, for many people, it solves all the actual problems semantic markup is supposed to be able to solve.
The article dismisses XHTML with little explanation: "all the ideology surrounding XML that never came to fruition".<p>AFAIK the goal of XHTML was extensibility and interoperability with other data formats, by allowing arbitrary XML elements from other XML namespaces to be embedded. It seems to me that this solves exactly the same problem (as microdata) and more in a much cleaner way. Why invent yet another format?
"XHTML provided no actual benefit"<p>Yes it did provide great benefits that are now being destroyed. The benefit was that we actually had working, up-to-date XHTML parsers in each and every programming language. Message to web designers: Some people have to parse the crap you put in those pages and it's not just the browser makers! I know HTML parsing was never an exact science even with XHTML, but at least we were moving in the right direction.
From the article:
"Unlike all the ideology surrounding XML that never came to fruition, Microdata is already being adopted by Google as part of their rich snippets to aid in providing richer search results"<p>O RLY:
<a href="http://www.google.com/support/webmasters/bin/answer.py?hl=en&answer=146898" rel="nofollow">http://www.google.com/support/webmasters/bin/answer.py?hl=en...</a>
Why it matters:
Dumb eBooks Must Die, Smart eBooks Must Live
<a href="http://ebooktest.wordpress.com/2009/07/21/dumb-ebooks-must-die-smart-ebooks-must-live/" rel="nofollow">http://ebooktest.wordpress.com/2009/07/21/dumb-ebooks-must-d...</a><p>Why Publishers Fear Metadata
<a href="http://www.knowthyshelf.com/?p=30" rel="nofollow">http://www.knowthyshelf.com/?p=30</a><p>Stop thinking it's limited to web browsing.