> Shouldn't there be a re-tag option, for community questions?  

Probably not.

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Community wiki questions are [editable by a much larger audience](http://superuser.com/privileges/edit-community-wiki) than regular posts, so you have full editing privileges there.

Just as 2k+ users who get [full editing privileges](http://superuser.com/privileges/edit) on all posts, you lose access to the [retag option](http://superuser.com/privileges/retag-questions) on questions you can edit completely, as it would be redundant: The *edit* option **replaces** the *retag* option. That's also the reason for the confused comments on your question: *We 2k+ users don't have the retag link on any question*.

If you only edit the tags using the *edit* option, it doesn't count as a full edit (e.g. towards the Editor badges).