It's not just that they were quick and agile, it's that they flew away like, ten feet after a single combo. They did that in other games too, but it wasn't a problem there.
Nero IS more suited to this game. I think they just stuck Dante in there so fans wouldn't get butthurt, but they did anyway. People can't accept change at all nowadays... For the record, I dislike Dante with a passion, and always have after DMC3.