It's pretty simple, anybody can ask a question, but not everybody can answer it. It's easy to wonder about something then ask someone a question about it, at that point you are neither adding knowledge to the person or impacting anything on them, but when the question is answered, the person that asked the question gains knowledge and as such you're different from when you asked the question.

Besides sometimes finding the answers to these questions take alot of effort, you might have to task yourself mentally or search the web for hours looking for a possible answer to a question that you've seen. Whichever way you see it, answers will always get more upvote than questions because although there would be no answers without questions, but the aim of every question, unless it's rhetorical is to be answered. Moreover, I believe that musing was made to reward answers, not really questions.