Didn't read all the posts so excuse me if someone already mentioned this;
Allow me to speculate:

level 1 cure casting bar |-|
level 50 cure casting bar |----------|

I'm thinking the mechanics is going to allow you to produce the spell anywhere during the cast.
MP and potency higher nearer the end of the bar.
Cast time balanced out by higher level's fast cast

and graphics adjusted accordingly on how far up the bar you cast ^^

Need ez system, esc key, to cancel