Currently the Tags core feature is using text names to refer to individual tags. Referring to the tags using an ID number seems like a much better solution overall.
It avoids typos or poor naming choices from being stored in the database forever (and in the MediaWiki: messages). It also ensures cleaner database results, allows for easier joining with other tables in the future (for outside extensions), and avoids the general nastiness of allowing (apparently) any character in the tag name, including question marks, quotation marks, ampersands, etc.
Awaiting vociferous opposition and a rapid close.