I actually appreciate the limitations set by the recast timer.

You have to actually appreciate the armory system. For all the flaws this game had, adapting to XI's 1Account multiple Job/Class was a flawless take, adding the simplicity and convenience to weapon defining your class. With this kind of great flexibility comes a bit of drawback and that's purely for preventing abuse of certain abilities. I think it's perfectly reasonable when looking at the picture as a whole.

Although OP has some great points.