Tagging still matters, like WordPress is forcing the tagsystem (since WP version 2.3. built in) over the category system.

I’ve never liked the categories or topic section, I’ve rather used the UTW tag system, now the native WP tag system.
There ae often posts which don’t fit into any of the category, but will flow nicely with a special tag like “video” or “movie”, so instead of having a twenty-something category list in the sidebar, tags are much more usable.

Tagging matters