On the surface, these feet do not look nearly as useful as the AF version, which offers an additional 5% CT/RC on spells when using the proper grimoire.
Celerity/Alacrity is one of the few ways you can get shortened casting/recast times while weakened. Aurorastorm yourself after a wipe and cast all of your R2s with Celerity. With a decent hMP set, you'll have plenty of MP to cast your 60% faster recharging raises.
A situational piece at best, but not a complete waste of an inventory slot.