Isn't this just a debate of the meaning of words when considering the actions of an extremely small sample?
It could be argued motivation leads to curiosity - maybe someone needs to get a job (motivation) and they wonder whether (curiosity) thet would be able to learn some skills that would enable them to get one.
I would suggest it's subbstantively about volition in learning. A motivated learner will be successful if given sufficient resources, time, environment etc. whereas an unmotivated person will not learn, not even after prodding them with a Big Pointy Stick. If they do change behaviour, and in the manner you desired, you've simply provided motivation - to avoid the nasty stabbing pain in the forehead in this case.