Maybe I’m old school, but this sort of bothers me. One of the nice things about rebooting is that it clears out old crud and gives you a reassurance that the system can bring itself up by its bootstraps. I can imagine live patching giving rise to a scenario where you have a machine that hasn’t been rebooted for years and when a power glitch finally brings it down, you find that what is on disk is different than what was in RAM and your kernel is corrupt or not bootable.
I think live patching would make sense if we had non-volatile system RAM (i.e. universal memory), but until then, it seems like rebooting is a pretty good sanity check that things are alright.