An additional reason to require comments is to be sure the negative points being assigned to the user who posted the question are justified and not arbitrary. Maybe the person leaving the down-vote doesn't understand the question because he or she has very little knowledge of what the question discusses. Or maybe someone is revenge-down-voting a question because the asker down-voted or somehow negatively impacted something the revenger did.
I just had a question get down-voted and it really baffled me because, as a user of the software, I really feel it is a valid question. On top of that, being new to Area 51, I was taken below the threshold for doing pretty much anything on this site. So someone just took away my ability to participate in Area 51 and has no requirement to answer for the action. It is very discouraging.
I was wondering why there there appears to be such sparse activity in Area 51 compared to other StackExchange sites. Is the difficulty in participating here the reason?