People apply wildly different criteria.

This is a feature.

It is a property. It means some aggregation. But that is inevitable given a single bit.

In short, I think the karma system is excellent and sets a high bar for being improved on.

It is excellent compared to no rating or only single-direction voting. But is quite inferior to e.g. the slashdot system. Even a single-click system that provides different buttons for different types of posts would be better.