I think that the up and down votes can stay but if and ONLY if a comment is left that supports that vote. So you could not process/send an up or down vote without leaving some type of comment. Perhaps have a minimum word count for this to ensure that people don't just leave a single letter or word as a comment as a way to get around it.
We in the Military are tasked to take decisions sometimes without real evidence, going only on experience, a gut feeling, or a combination of both. Afterwards though, we are often tasked with explaining why we took the actions we did. This should be reflected here too, otherwise RP becomes a Military version of FaceBook, where very few comments have any real value, and "likes" mean absolutely nothing.