What king 500 years could do that? (Well okay, maybe Suleiman the Magnificent, but that about exhausts the list.)
500 years ago puts us in 1525, which is still in the transitional period of Medieval kingdoms becoming actual states. The kind of absolutism you're thinking about is still about 100-150 years away from coming to fruition. Medieval kings were almost entirely reliant on their vassals to be able to marshal any power whatsoever: if an important vassal decides he doesn't want to fight in the king's war, well, the king can't exactly force him (see e.g. the Burgundians in the Hundred Years' War--and this involves the most cohesive European monarchy!). You're starting to see efforts by 1525 to reduce the power of nobles to act independent of their liege, but they're certainly not there yet.
But keep in mind the other luxuries people today enjoy that the kings of 500 years ago can't. The ability to see all of your children survive until, well, your own death. The ability to eat, say, fresh strawberries in the height of winter. The ability to know your wife isn't going to die giving birth to another kid. Hell, pretty good odds your bed is larger than a king's bed from 500 years ago, and more comfortable too.