I know Wikipedia has the answers to a lot of the questions posed here, but I've been seeing a lot of answers by people just posting large paragraphs from there or say, on a Star Trek question, from Memory Alpha without adding much more of their own explanation. Even if they cite the source and put it in block quotes, why not just rewrite into your own words? We might as well all go over to wikipedia if we're just going to copy and paste those pages into our answers.
We might as well all go over to wikipedia if we're just going to copy and paste those pages into our answer
Or for those who don't get my sense of humor: I think people should stop asking questions that can be answered by a copy & paste from Wikipedia!
In my opinion, if a c&p from WP is sufficient to answer the question, then that's all that should be done. The OP didn't bother to make that little bit of effort before asking, after all. Why should the person answering work harder than the asker?
It seems that this will always be a significant problem, because Wikipedia/Wookiepedia/MemoryAlpha (etc) have been around for a long time, and have a lot of high-quality information. This was not the case with (e.g.) SO, where there were well-documented (e.g. early SE podcast episodes) problems with the existing sites.
However, while SE sites are wiki-like, they are not designed to be an encyclopedia. There are significant differences between an encyclopedia and Q&A, for example, scope (questions are specific), depth (questions hopefully look for more insight), and impartiality (questions care less about this than a 'dry' encyclopedia).
I think @neilfein is right: voting is the way to fix this. If there doesn't appear to be any way to answer the question well without regurgitating another site, then comment on the question, down-vote it, and/or vote to close it. If the question is ok but the answer is not, then, again, comment on it, down-vote it, and/or edit it.
All SE sites have poor answers. As long as there are also many good answers, which will float to the top (via votes/acceptance), then that's not a serious problem.
This is partly the nature of the site and partly the nature of the questions.
The questions: if you ask factual, closed questions, "which is the most", "what was the name of" etc you are more likely to get Wikipedia copy/pastes. If you ask open, "why" questions you will get less or no Wikipedia copies.
This is partly the reason for my question, "What about subjective questions?"