AST: why can't we use time dilation on ourselves?

[Elleia]

Probably so you can't time dilate Luminiferous Aether and get 30 seconds of MP Refresh.

Celestial Opposition thankfully still works on it

Couldn't they just make it so Time Dilation only effects the card buffs and HoTs? After all, it doesn't extend the length of cooldowns on other classes (hence why Time Dilation on a WHM using Shroud of Saints won't extend that effect either). That way, an AST could use Time Dilation on themselves after an ewer card to help with mp management.