I get what you mean, but wouldn't that just kind of defeat the point?
"You get all theses cool abilities to learn and find!"
"Except for when you set foot in here, then you only have these ones, oh and they work differently then they did outside of here too."
At that point you'd effectively have two separate classes trying to live in one, it would be SCH and SMN all over again, only you get forced into one depending on being in the over world or an instance.
