It seems that Wikipedia only requires a link back to the article as attribution. That's according to an answer from one of the questions you posted.
In general, I think it's better to write original content for tags, but if a paragraph from Wikipedia is apt, then including it with the link shouldn't be that big of a deal.
I agree though, that anything more than a link (e.g., a licence agreement, or requiring the entire article, not just a part) would be too much for the tag wiki.
