So, how many killer apps have been made impossible by the GPL and other copyleft? We can't really know. Want to structure Wikipedia's data, add value to it, and resell it? Sorry, you'll need to operate at a loss and offer your data for free because of Wikipedia's share-alike license. The fact is, we can't see all of the awesomeness that doesn't take place due to copyleft enforcement because fear of legal retribution means that none of this awesomeness can exist in the first place.
There is nothing stopping you from creating an encyclopedia based upon other licensing models. You must start from scratch and get a group willing to create that content in some fashion with those other licenses. Such encyclopedias did exists and still continue to exist in other contexts, even though some have folded up shop. Wikipedia wasn't even the first electronic encyclopedia: ever hear of Encarta?
You are also free to use Wikipedia's data, add value to it, resell it, and make money at the same time. There are many people who are willing to do that and do so at a profit. Nothing in the CC-BY-SA license used by Wikipedia prohibits you from making a profit, it just spells out the terms and conditions for reusing that content. If you don't like the license, use somebody else's content. What I see here is a complaint that you don't like the license and are expecting others who don't agree with you that perhaps they should adopt your philosophies for content usage.
If you really think there might be some sort of advantage with some other licensing model for an encyclopedia, start it up and convince some others to help out with developing content. Pay them for it if you must, but find some way to get it to happen.
It is possible that many people who contribute to Wikipedia do so simply because they have something interesting to say and don't care about the licensing model at all. You might get many or most of those people to join in your project too. In fact, I know that there are some who participate on Wikipedia who explicitly do donate all of their contributions into the public domain as a whole and don't accept copyleft licenses. There are also purely public domain images on the Wikimedia commons for you to use, including newer stuff that isn't in the public domain due to copyright expiration. If you want to prove that having stuff in the public domain is useful and can create some useful applications: prove it. The content without a copyright is available for you to use if you but search for it. Wikipedia isn't a solid wall of copyleft content as is implied here.
Thank you for the clarification about license diversity in Wikipedia. I am basing my thoughts on the license notice at the bottom of each page, which is CC-BY-SA.
You're right that it's not effective to simply talk about what I think is a sub-optimal license, and I'm not interested in recreating Wikipedia just to prove a point.
I think that you did, however, brush off my point: it's not about what terms I want, or what terms any person in particular wants. It's not about which particular pieces of information have which legal restrictions. It's about the innovations that won't happen because there are restrictions on the uses of that information.
It's about not wanting to threaten people with legal ramifications or make contributors feel like they're backing freedom when they aren't. Because really, that's what a license is: a legal threat masquerading as a platform for freedom.