Cheap? Not really. Dlanor isn't a character that really gets to benefit much from Metaworld carrying over. Of course there is no power cost for the move, because that's the way it works i.e. you can use the Meta World super as many times as you want while it's active.
For someone such as Dlanor, the animation of her super takes a fair bit of time in that IF you successfully land it, you will be able to perform the Meta super twice at best. And this is when the Metaworld bar is filled at 100%. Note that when Mugen is in the win state or while the next round commences, the Metaworld bar continues to deplete.
I do agree with you on the missing sprites of the Metaworld though, it may be a bug. Then again, this character still has some bugs.