It's probably a reflection of the size of HN. The more popular it gets the more people are flowing in at the bottom, to keep the place from descending into mayhem the karma thresholds can be ratcheted up.
200 still seems pretty low though.
200 doesn't seem too difficult, it just appeared strange that when I finally got there it disappeared 2 days later.
Just write a few more insightful comments or submit some good stories and you'll probably be able to downvote again.
In any case, why isn't the threshold value set dynamically? Maybe something like "if the user is within the top 70% of karma earners for the past week AND within the top 85% of karma earners all time" then allow them to downvote. This way it always adjusts to the traffic on the site and doesn't need to be manually changed unless you want to tweak the parameters a bit.
My daily reading list is usually just about exhausted by the time I go to bed, if HN gets any bigger I'll have to get more selective about what I read.
So much interesting stuff gets posted here.
I can't downvote topics. [3446 karma]
As someone else said, if a topic is broken -- spam, stupid or otherwise useless -- it should be flagged appropriately. My two cents, or probably about six cents worth 1 cent in 1987 values.
Seriously, while down votes are needed sometimes, I think they are overused. I often see a legitimate comment voted down because someone apparently disagrees with its contents. This is not what down votes are for.
In other news, "they" didn't laugh at Einstein or Newton, but they did laugh at Bozo the Clown....