No worries at all - the button is pretty inconspicuous (on top of the EFB) - and I made Tom make one (before the tab was always on) - because I thought it looked odd to enter a "cold and dark" cockpit and the laptop is running.
Background story here is that we have EFB´s in our real aircraft, too - of course. Procedure is to shut down the EFB when you shut down and leave the aircraft, but some people simply forget (he who is without sin may throw the first stone!) and when the battery goes dead, so does the display of the EFB (even though the tablet itself is still running in its docking station). So sometime during the night the tablet will reach low power and go to sleep mode. But for some odd reason it will not wake up from it again, UNLESS you take it out of the docking station, flip it open, and hold down the power button for a few seconds.
The problem is - we are not allowed to do that - it´s considered a maintenance task. So basically if you are on an outside station in the morning with no company maintenance available, you would have to contract a certified engineer, fill out a bunch of paperwork, do a million phonecalls (incur a few hundred Euros of cost) and delay the flight for a minimum of one hour. Or break the rule, take the laptop out, start it up and be done with it. Which I would never do, of course.
Hence my obsession with the power button
Cheers, Jan