As a desktop user, and considering I have to pay the power bill, I prefer to shut my computer down whenever I don't use it, why should I keep it up aside showing off the size of my member by having a proportionally huge uptime? For most users it serves no logical purpose to have an always on solution, and there's no reason why our boot time should be suboptimal.
A good point, but note that "not always on" does not necessarily mean "needs to boot". That's why hibernation was invented. There's no reason you couldn't hibernate a laptop, and have huge "up times" with the power removed. The question then becomes what kind of hibernation support is available under Linux.
