We each have 25 votes per day. I do believe that qualifies as a quota. I've just been going over some of your answers and so far haven't actually seen a problem in the voting. e.g. [This answer][1] got a couple of downvotes, complete with an explanation. Although you apparently don't accept that explanation it has been posted in is perfectly valid. ANY security software that hasn't been updated in 2 years is worthless.

Some of the reasons a comment should not be required for a downvote are:

 - It encourages retaliatory voting patterns
 - It would in many cases result in a whole lot of arguing, which is not what this site is about
 - Why should a downvote require a comment when an upvote doesn't?

  [1]: https://serverfault.com/questions/96099/security-and-protection-for-win-server-2003/108168#108168