It pretty much comes down to this: karma is a tool. If it sucks or is worthless, it very likely could be
a Nikon the problem is the users, not the tool. Without a post indicating why a smite or applaud is applied, it doesn't provide a lot of usefulness. But I think it COULD be a good tool to find out as a community what people find useful and contributory, and what is uncalled for and unappreciated.
Now see I'll probably get negative karma for this post because all the sudden I'm a fanboy because I tried to employ some humor on a CANON website at the expense of Nikon (who does make perfectly good cameras.)