Why Wikipedia are wrong to nofollow their links

I realize it's far too late to comment on this, but I rarely if ever crack open the old blogger edit window.

Nofollow is good-ish idea. It's perfect for blog comments where you don't have the time to moderate everything but don't want to pass on any benefits to spammers.

What it manisfestly won't do is deter the spam in the first place. How can I tell this?

Well from the comments I get for a start.
  1. They are clearly-auto posted, so there is no reason not to try spam. It takes no effort.
  2. They are often not formatted in HTML. Sometimes they are plain text - just a URL, sometimes they are in Forum pseudo tags in square brackets ([url=]http://myspam.com/[/url]) so they aren't even trying to get/checking if they get pagerank.
What this means for Wikipedia is that they won't slow their spam onslaught, but what they will do is decrease the quality of search results. Wikipedia has huge pagerank authority. It is also for the most part very well edited. The upshot of this is that a link from Wikipedia passes on some of that huge pagerank because it should. It will make search results better as a whole.

Google should make Wikipedia a special case and disregard their nofollows.