I see a questions that should be community wiki as there's a comment saying that with 5 upvotes. The user doesn't have enough rep to have the community wiki option, I go to edit the question, and I can't make it community wiki. Why not?
Because that way leads to abuse and people kicking other people's posts around.
Currently there are four ways to turn a post into wiki:
If you see a question that you feel needs to be wikified, flag it for a moderator and explain why. Don't just say, "Should be wiki". Instead, something like "This question is open-ended and sounds utterly like fetching advice and best practise than an actual concrete answer and should be wiki" helps.
All authors have the ability, regardless of their rep level, to set their own posts as wiki. Even the drive-bys can set their questions to wiki on first go.