I was initially using the Desc field for keywords and that was not good enough, claimed the community.
So I jump started the Tags by batch processing all extensions with a script to filter out common words to make auto tag items.
The only way for Tag items to show up missing is because of an update to the extension. Therefore, the extension maker should be contacted to correct this error. It is likely that their local copy of the .info is missing the Tags field. If it is not corrected by the extension maker, i.e., update his local .info, then the tag will come up missing on the next submitted update.
If we have to "fall back" to "inserting" the Desc to Tags, then that defeats the purpose as the Desc field was, and still is, not good enough.