It'd be nice to tell a poster you like what they've said without having to hit reply and write something when at the time you have no deeper feeling than that you liked what he said...
And I never thought of that! You be awesome! Still unnecessary clicks but does keep me from having to think up words when all I wanna say is 'I like that!'
I think that it is a really good idea, particularly if a really good scene is viciously attacked by a poster, who winds up being outvoted by a 10-1 margin of "like/dislikes". It adds a degree of context for other members to evaluate the post. While everyone is entitled to his own opinion, context can be important as well in fairness to the scene and its models.
Webmonkey suggested adding that feature, many years ago. Back then the idea got several thumbs down!
Something about not wanting comments to be subject to vote.