John Gruber @ Daring Fireball does not like vision videos: The Type of Companies That Publish Future Concept Videos:

“DeVilla isn’t the only one who accused me of Apple-biased hypocrisy regarding my stance on Microsoft’s “Future Visions” vs. Apple’s “Knowledge Navigator”. It is true that when I linked to Andy Baio’s post about “Knowledge Navigator” a few weeks ago, I didn’t add any commentary.
But the exact same criticism I have for Microsoft today applies to 1987 Apple. “Knowledge Navigator” encapsulates everything that was wrong with Apple in 1987. Their coolest products were imaginary futuristic bullshit. The mindset and priorities of Apple’s executive leadership in 1987 led the company to lose what was then an enormous usability and user experience lead over the rest of the industry, and eventually drove the company to the precipice of bankruptcy. That 1987 Apple was a broken company is so painfully obvious from today’s vantage point that I didn’t think it needed to be mentioned.” [links and emphasis added]

This applies to planning as well, which is very much about “imaginary futuristic bullshit” which most people either (a) can’t grasp, (b) dislike, (c) naively believe religiously, or (d) find underwhelming.
I think you need both a vision to shape direction and concrete incremental decisions to move you in that direction. Whether a vision helps or hinders incrementalism depends on the vision and who it is pitched to. (The classic argument of “Perfect being the enemy of the Good” often delays useful projects to the point nothing is accomplished). I am sure Steve Jobs had an internal vision, but he did not want to reveal it before it was ready. He was dealing with private goods.
Public works on the other hand cannot really be sprung on the public anymore. Hence visions, and plans.
A major downside is getting locked into a bad vision, a misguided line on the map, or a poor investment strategy because the vision or plan became an implicit contract. Unlike vision videos, which if wrong or distracting can easily be discarded, the plan somehow becomes permanent.