One scenario that immediately comes to mind is frequent flyers. I note this since I just took a series of flights a few days ago. Say you want to be productive during your six hour red-eye flight. That involves several repetitions of "we are now preparing to descend and land, please turn off all electronic devices at this time." If you're a business user who goes through this on a regular basis, a long boot time could indeed get annoying in a hurry.
I generally just put the laptop to sleep by closing the lid. Macs are generally quite happy about that - the superb power management is one of the major selling points.
On a normal flight "switch off electronics while landing" happens once. If you think otherwise you have failed at flying (sorry, couldn't resist re-using your phrase there).
