Further to Debra I would urge you to separate the tool from the professional. What your ambition should be is to become a great planner/scheduler. That will require tool skills plus knowledge of planning (eg scoping, depedencies, communicating with the team, influencing skills etc). Theoretically you could be a great planner no matter what the tool, even a pen.
Then it is always worthwhile getting more skilled in the tool, mainly so you dont waste your intellectual energy on the tool, rather you are focused on the project. The PMI scheduler accredtiation is a good objective to have. Getting better with the tool is also useful.