Who shuts down their computer anymore anyway? Between sleep/suspend and hibernation, my systems rarely get an actual reboot. Did Apple ever get hibernation going in OSX? I only remember seeing them use sleep mode.
I have Postal or Postal 2 around here somewhere for MacOS..
I would say most people shut down, rather than sleep/hibernate. Especially laptops, which are prone to heating up in a bag if they are left asleep, and which take just about as long to get out of hibernate as they do to boot anyway and the way sales are going these days will outnumber-if they haven't already-desktop users.
There's a lot of effort being put into making Windows and Linux boot ever faster and that's because users demand it.
Don't under-estimate the value of a fast booting OS is to the average user. It matters, Microsoft knows this and Ubuntu's targetting a 7 second boot time this year apparantly. They wouldn't be devoting resources if it didn't matter to the average user.