Before structured data Google preferred microformats. They still do, but for things like last modified, quick overview of categories, site content update status, or other legacy knowns. It's almost real time, very quick index changes, with hubs to boot. Very much better to have these rather than ETAGS or 304 + AI trying to figure relevant changes.
Structured data has it place, and Google def does prefer it now for data semantics, schemas, mirroring, and relationships but the good ol microformats are still preferred for general updatability and indexifyingness. This may and will change in the future, but the legacy microformats will never really be "unsupported".
So what's the solution? Use them both! Add Atom as well, go all out