Accessibility
Because some microformats make use of title attribute of HTML's abbr element to conceal machine-readable data (particularly date-times and geographical coordinates) in the "abbr design pattern", the plain text content of the element is inaccessible to those screen readers that expand abbreviations. In June 2008, the BBC announced that it would be dropping use of microformats using the abbr design pattern because of accessibility concerns.
Read more about this topic: Microformats, Evaluation of Microformats