They definitely need to be updated, the look is not that pleasant, it's 2009 graphics, I think simple touches would make it look fantastic, just redefining the textures of the creatures, the architecture, not changing anything drastically, just... hmm.. polishing the original worlds would help instead of focusing on making other Spiral Worlds.
Hmm... you can even make the original worlds more difficult to make it fun and challenging, definitely Krok, some of Wizard City, Mooshu seems a bit short in comparison to the next world.
P.S. Wizard City's (in general) is a bit corny with the slow pace, same spells etc. and the battle music needs to be a little more, hmm... fierce, faster? It's too slow paced. I hope I gave some new insight! Peace!