The key is that microformats fuse user experience and data transmission format. They are simultaneously both just html and just xml. Since microformats are just html, their user experience is the html user experience, meaning they can be integrated into rich internet applications by using standard javascript, css and other html tricks. Since microformats are simultaneously just xml, they are a natural as a data transmission format for emerging new web application frameworks like ajax. By the same token, microformats can be made directly consumable by web-based services. But, here's the kicker, since microformats are still just html, they can fulfill the data transmission role without requiring any sort of translation prior to presentation to the user. In sum, the combination of html tradition with xml rigor allows microformats to do two jobs for the price of one.

Rival approaches like structured blogging or separate meta data URLs just do not provide this fusion without a whole lot of extra plumbing to translate between incompatible xml formats. In spite of the hesitation expressed by some, microformats seem like a no-brainer.