As a caster (blm especially) standing still and casting is the focus.
We can stutter step, and we have swiftcast.

I was thinking if we could reduce swiftcasts cooldown by half,
it would allow for a lot more movement.

It wouldn't raise DPS a whole lot, but it would help with the mechanics and the trends they are heading towards. (see sephi X)

Now I know that the dungeons are doable as a caster like blm, but this would just add more usefulness to swiftcast, without creating a tonne of other problems.

I don't see any negatives at this time, but I don't play as a healer, so if there is any real negatives anyone can bring up i'm all ears aswell.