@JaceK, if we removed any system on the basis that it could! turn into something nasty or be abused, we wouldn't even have a forum ;d.
If anyone was being arsy about their Karma, obviously they'd get moderated, but I suspect in that situation, as indeed in many situations, it would be the inherent arsiness of the person that was to blame, not the Karma system itself, heck people are quite good at finding reasons to be arsy on their own without us having to imagine further
Personally, I like being able to thumb up a post and say "thank you" to someone in a tangeable way and that's what I've seen Karma being used for since we removed the thumbs down option, which is all it was ever intended to be.
I am afraid there isn't a way to have users disable display of Karma if they don't want to see it, though I agree that would be a nice option to have for those who don't care about the Karma system, as it is your best bet is to just treat the karma system like a public toilet.
it's there for anyone who wants to use it, if not your free to ignore it, and the staff promise to keep it clean and stop it from stinking either way .
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)