Damn... You've all been at this for quite a while for Roy to be the inly relevant FE character... Now I see why you're all so desperate for info...
Also, why was Palutena vs. Medusa ever a debate? Seems prettyobvious to me who the better chouce is and I've never played a single KI game.
Roy did not have serious competition for the third FE character spot until FE13 was announced, which was September 2011. 1.5 years ago is not a long time ago.
As for Palutena vs. Medusa, the reason why there was so many people backing Medusa was because:
1. Medusa was seen as two-fer (female and a villain), killing two birds with one stone.
2. The general perception among Smash Bros. fans that villains are more important than side characters (though they tend to forget that in Smash Bros. that sidekick character typically gets in before the antagonist).
3. They felt Palutena was too passive to be in, and that she could not fight.
4. They felt Palutena was already ruled out due to being a part of Pit's Final Smash.
I might be forgetting some other inane reason they used, but that is pretty much it.