What are your thoughts? Are you even agreed that an rpg is the best genre for this? Which is more suited? 2D which usually has more artistic freedom and expression, or 3D which allows for ultra realism unseen in 2D?

I don't think that graphics is the solely way to convay a feeling, mainly because graphics still look like graphics.
I think that to succed in conveying sadness it should be with the help of music and/or dialog.
This is something that can be in all genres, it doesn't mather if it's an rpg or not. And for the graphics, with prerendered you will be able to make the graphics better then have it in real time 3d and therefor can lean on the graphics a bit more for conveying feelings.

If it's cinematic, I'd go with a cinematic consisting of a slideshow of black and white images. I've seen it done in several games and it works great combined with the right music and the right tone of voice of the narator.

I'm talking about an actual game. Just wondering which people think is better over the other.

The Final Fantasy games are very good at invoking emotion.

Sanitarium is another excellent example of filmography melded with gameplay invoking all kinds of emotion. If you find a copy I'd get a hold of it, I think it's pretty rare these days as ASC are out of buisness
http://www.cdmag.com/articles/008/059/sanitarium_preview.html

If you get a hold of "The Incredibles" film on DVD, the extras talk about tons of directorial devices to create a certain mood for scenes.

The selective use of colour and light, a characters musical theme in a minor key, decent dialog, all devices at your disposal.