Just wondering, I've been able to down vote for a few months, but recently, my karma hasn't gone down, but I can no longer down vote comments.

Why would that be?

The karma needed to downvote moved from 200 to 500.

There's an enforced ratio of downvotes to upvotes that you may have hit. Also: comment more.

Hmm, encouraging commenting as a means, not as an end, is engendering a culture of under valued contributions...

I've been a member since late 2009, but I've made 2 or 3 comments so far. My case is not atypical. Maybe there's a better way?