Cura became a novelty when Orison Pantaloons were released. It's not hard to make Curagas free so the idea of a "cheap" Curaga is just silly.
Well, that depends. Maybe if you have 5 frontliners (or even 6, if you're letting yourself get AoE'd too) all taking roughly equal amounts of damage, it isn't hard. That ain't always how it works though. I honestly can't remember the last time I've partied with 5 frontliners as a WHM.
Also, Curagas will get you to capped hate rather quickly; Curas will not. Of course, if you're in a situation where you have to be using rapid Curagabombs to survive, chances are Cura would not cut it anyway. But that was why he was saying that he hopes Cura 3 is potent enough to suffice for more situations.