(Updated) Rich collaboration or wiki?

Bill Ives (Portals and KM) has written a peice talking about collaboration successes with IBM Lotus Quickplace. This made an interesting contrast to Bill's recent focus on enterprise use of wiki's about which I have blogged and bookmarked. I found myself asking why would a company choose something like Quickplace instead of an enterprise strength wiki such as Confluence from Atlassian. Isn't a good wiki platform going to give you much more bang for the buck? I need to think about this more.

[Update: Having thought about this, here's my take on cooperation modes using a wikiCooperation modes using a wiki

So tell me again why I would buy something like Quickplace?]