I use Swiftcast pretty often for a quick Holy on dungeon pulls, because it makes a significant difference there.
I wouldn't have expected Swiftcast to make that much of a different with single-target dps spells, outside of movement, in which case it's entirely situational. Maybe on SCH or AST it allows for weaving?
That said I've played AST the most in higher content and it doesn't really need any more weaving capabilities.

Either way, unless you're expecting people to be dropping every 60s, you should be able to use a Swiftcast outside of Raise, whether that's for DPS, or a quick AoE GCD heal because all the rest are on CD, or whatever.

Prog and Clear parties I can see it being a big risk, and if I healed those I almost certainly wouldn't risk it, but outside of that... it's not a huge deal.