Suppose a new user has a question to ask on a new meta site about badges. The meta site is too new to have a badges tag and the user is too new to have enough rep to create tags.
It would be useful if all of the per-site metas had a selection of generic tags from the start. As well as allowing low-rep users to use common meta tags, it would also make it easier for someone wanting to retrieve data on multiple meta sites from the data dump, as tags meaning the same things would have the same names across multiple sites.