Honestly speaking, I feel the reason "You need an absurd amount of SS to gain X amount of cast time reduction, so get DET better!" to be invalid.
Reason being, it also takes an absurd amount of DET to have a noticeable increase in healing power (7~8 DET = 1 mind IIRC)
So...why is only SS being discriminated for "requiring absurd amount" whereas DET gets a free pass? =\