It would be helpful to associate a comment with a vote. Perhaps when a user clicks on the vote button, he/she could be prompted to submit a comment. The comment would then be displayed as usual in the comment section, but if a user pulls up a list of voters on a given issue, the associated comments would appear there.

JIRA supports voting and comments, but when you review the votes, there is no simple way to know what the voter was thinking. Manually mapping between the comments and the votes (in those cases when a user has done both) is non-trivial, especially for popular issues.

Now that I think about it, maybe a user should be prompted for voting when he/she submits a comment, just to cover both sides.