I srsly don't buy the tressfx flowy I'm your Venus hair bullshit they're selling as the reason 360/PS3/Wii U aren't 1080p.
It won't be the hair alone, but the fact that it and all the other characters are 3D rendered. I don't think this is a technical shortcoming, but rather an artistic choice. Indeed, I'm surprised DF are confused why the game isn't 1080p like the recent
Rayman games. To me it makes good sense, given what the games are.
Rayman is built of hand-drawn sprites and backgrounds, so literally the only way to increase their smoothness and detail is to raise the resolution.
Child of Light has hand-drawn backgrounds, but the characters are 3D objects. Simply raising the resolution won't help as much with them (some, but not much). What you want for 3D objects is good AA, and the most effective AA process is supersampling. By downsampling to 720p on the lower-tier machines, Ubisoft can achieve better edges and detail on the characters, which is mostly what you'll be looking at.
There is a cost of increased blurriness for the backgrounds (2D art is hurt by lower resolution, and downsampling doesn't change that). But the soft-pastel watercolor look of
Child of Light is less damaged than the vibrant, squiggly
Rayman world would be.
It seems Ubisoft chose a softer look for PS3/360/Wii U, rather than a sharper look but with worse jaggies. I think that's the right call for this game.