When Steve Jobs does his song and dance, he delivers his message to an eager and receptive audience, and there's no question that his mastery of public speaking helps promote his message and causes even those who aren't Apple zealots to take notice. I'd hazard a guess that this skill is also a huge arrow in his leadership quiver inside of Apple
It's rare to find great leaders that can't speak to a crowd and get them riled up about what they are promoting. I'm sure there are cases where introverted, soft-spoken leaders have been successful, but most often, the ability to speak well to an audience is a required talent. Unabashedly promoting one's organization and, often, oneself, is a fundamental skill that anyone who is now a leader or wishes to be one must learn. The good news is that it can be learned.
At the Needham Growth Conference, I attended roughly 25 presentations by companies - both private and public. There were some poor speakers, some mediocre and a few really good ones. As you might expect, the quality of each presentation had little to do with its content. There were great presentations by CEOs of companies dealing with a boat load of stock option issues, their stock in the toilet, and there were crappy presentations from squeaky clean companies growing 300% year-over-year.
Generally speaking, the boring speakers lost their audiences, physically or mentally, by the time they reached the halfway point of their speech. The great speakers held their audience and were surrounded by people that wanted private time with them after their presentation. Good speakers walked away with dozens of business cards from potential investors and poor ones ate lunch by themselves. See a pattern here?
I've said before, that I believe that leadership and management are separate disciplines. If being or becoming a good leader is the goal you seek, practice being a good speaker (yes, it requires practice), prepare (a lot) before you speak, have something meaningful to say and ban timidity (but not humility) from your presentations. Use the force, Luke.