Hm, now that I think about it, my theory fits almost perfectly with spiraldoor's theory about evilness spreading like a virus (I didn't put that in transparent text, since I only mentioned something already known about the plot)
I also heard Haruka is disappointed with the amount of levels

Well Haruka, If I do my math correctly, the game still has a pretty big amount of levels. Let's remember that 60 levels makes enough for a full game, and Rayman Origins proves that. If that's not enough for you, half of the levels will feature an invasion mode (which, if I'm not wrong, are the last 30 levels of the game), and are basically like the comets in Mario Galaxy: after you finish a level, you are introduced into a new level with the same settings but with different objectives. The attack of different enemies, new platforms, and the excellent remixes (mexican version of Once Upon a Time, for example) will probably be enough to give a completely different experience.
We have 40 levels from Origins, but that's not a big problem... especially when they're a bonus and you're not forced to play them

You still have 90 gorgeous levels in the main campaign.
Also, we have Kung Foot, a Challenge Mode, The biggest selection of characters in the Rayman series, and some sort of bingo-thing where you pay (probably lums) to get tickets to unlock stuff, like the Origins levels. It also has a gallery of "Creatures", which probably means we'll finally have a gallery that explores the Glade of Dreams' beautiful fauna :'D and probably collect more creatures with those tickets.
EDIT: I found this,
Apparently, it's some french reporter talking about Legends. Not a big spoiler, but it shows some new levels.
-Blue Teensie Wizard confirmed to return as a playable character.
-Goth Barbara?
-Apparently, Tricky Treasure Chests will be back in Back to Origins
-Baby Dragon Chefs return as enemies on the main Legends campaign.