Molly,
I agree that sometimes a comment is much more deserving than an original reply to receive a recognition, so stars should be allowed for those too. Many times, the first reply is just a request for clarification and the real answer comes later.
However one of the problems with the current star system is the absence of any official guidelines on what they mean.
We have for example opinions like in this quote from RL above: "From the comments I read:
Extensive help with attachment is a 4 star.
Good and helpful answer is a 3 star.
Incomplete answer is a 2 star.
A 1 star is a reprimand for not reading the question properly or giving misleading information. Actually a 1 star is probably viewed as an insult."
This is quite arbitrary, co
mpare e.g. with my post in
this thread.
Why sould a single star be considered anything negative? It is still something shiny!!
I don't think negative ratings should be allowed in general and I would propose to reduce it to a simple binary system (Mis-paraphrasing Hamlet: star or no star, that is the question). If you want to support negative ratings, change it to e.g. 1-2 stars or 1-2 thumbs-down.
Another possibility would be to allow marking an answer as incorrect or misleading, an option that should be accessible e.g. only to enthusiasts.