If I understand correctly, the community wiki flag only has the following effects:
- Posts can be edited by people with lower rep threshold
- Question and answers receive no rep gain from votes
I think CW is appropriate for community-building questions like Tools that every do-it-yourselfer must own because they are basically polls and would otherwise lead to large rep gain just for being the first to suggest a cordless drill, without solving anyone's problems.
But I don't understand why something should be CW just because there is not a single, clear, objective best answer. Questions of the form "I want to do X, but I haven't done it before and don't know where to start, what advice would you offer a beginner?" are completely fair and useful to many. They can become a great collection of advice, judgment, and experience, even though the questioner didn't know enough to ask a more specific question.
For the questions you quoted, I would expect that a few good answers receive many votes and that some other bad/wrong/useless answers receive fewer votes. The questioner may accept one of the best ones, or may decided not to accept any and instead just vote up all the good ones.