I'll tell you where boot time matters, when you are building systems. I've become very accustomed to the super fast boot time of virtual machines - it is painful almost to have to reboot a physical server. When you're doing this all day, every day, it is a major factor in productivity. Multiple reboots are required to build a Windows server from scratch, join it to an Active Directory Domain, install various roles and features, get the updates caught up, and install whatever third party applications might be needed.
My main desktop boots in seconds, but rarely needs to, so no, it's not really that big a deal. My laptop, since I am constantly moving around with it, it's nice that I can flip it open and boot up in seconds to do what I need. Some days I'm in one place, boot it up and never reboot until I shut down at the end of the day, but other times I am setting it up and taking it down several times.