A) Allow one to rate a single post rather than having a "Rate All" button on each.

B) Instead of a 1-5 scoring system, a -1 through 3, or -2 through 2 system would be preferable, where 1 or 0, respectively is "Neutral". The verbal descriptions from lowest to highest are fine though and should remain the same.

Alternately, a similiar result could be reached more easily by setting "3 Neutral" as the default and not messing with the numbers, but I think 0 or 1 as the Neutral setting is more intuitive.

C) Set a default for all posts, such that unrated posts are voted as Neutral when "Rate All" is selected.

This would promote rating posts, as one wouldn't have to select a rating for each and every post, just the ones they wanted to mod up or down.

Of course, it might also moot suggestion A.