one situation where phone boot time could be critical.
My grandmother (92) carries a cell phone for emergancy use only, it's turned off unless she needs to make a call.
In an emergancy, I could very easily see a 1-minute boot time being critical.
now the phone she uses isn't a smartphone, but the point is that just because you leave your phone on all the time to receive incoming calls, doesn't mean that everyone will, and for those that don't, the boot time is significant.
on my laptop I don't care much about boot time, but that's because I so seldom turn it off, it goes from external power at home to external power in my turck to external power at the destination...
I don't use suspend, but I don't boot it more than once every couple of months.