I would have to agree with Matthew here, further restricting tag creation (by forcing them to create a tag wiki) would only really prevent people from asking their questions.
The creation of tags is already limited to users above 200 reputation so those users should already have at least a small idea of how the site works and there are also additional restrictions:
The new tag will now be available for all other community members to
use, without needing the new tag privilege. It will also show up in
the moderator tools new tag report.
However, note that:
- new tags will be automatically culled and removed from the system
if they are not used by at least 1 other question in a 6 month period.
- meta tags, tags that cannot stand alone as the only tag on a
question, are not allowed.
So as well as the moderators being informed that a new tag was created (so it can be quickly deleted if needs be) if it is left unused on any other questions it will be deleted as well.
I think the current level of restriction is a happy medium between preventing their creation and allowing responsible creation.