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][1] 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.


  [1]: http://superuser.com/privileges/create-tags