Only thing I could see this getting used for is Bloodrake spam, assuming this even lets you do that (that is, if it zeroes the recast of Unbridled spells too), which I'm guessing that it does not. Recast on Unbridled spells is usually not paid any attention to due to the fact you can normally only cast any one of them every 5 minutes without some sort of JA reset, so I don't even know what Bloodrake's recast is; I'm pretty sure I remember it having one of some kind though.
If not that, there need to be some more/better Unbridled spells released before this would see any real use. Ever since Azure Lore was updated to provide constant Affinity effects, it's actually pretty damn good if used properly (helps a bit if you have the proper relic+2 piece to add 10 seconds to duration)