I do think there's something deeply psychological about our knee-jerk response to this question. Do you feel judged for not making your bed? Do you have an underlying sense that you'll be embarrassed to see "how you really live" (bed unmade) but you only make it when company's around? Does leaving it unmade feel like liberation from paternal oppression? How about this: does making your bed give you a sense of peacefulness and order? Do you crave those things?
Growing up, our mother made her bed every day, but only occasionally would insist that we make ours. But putting on clean sheets was when we HAD to do things her way: with a nurse's training, it was hospital corners all the way. And you had to use a fitted sheet and a flat sheet--no skipping either one. The flat sheet and bedspread had to come up "just so" to within 3 inches of the top of the bed, then folded back down ,together with the bedspread, the pillows placed on --open side of pillowcases facing out--then the covers pulled back up over the pillows, and finished with a stiff tucking-in under them.
Fast forward to my adult years--I was hit or miss with making my bed, but preferred it made. The older I get, the more I have come to enjoy how it looks, and how it makes me feel during the day to walk in and see it made. Even if the rest of the room or the house is out of kilter, having the made bed gives the illusion that it's better than it really is.
I do use a mattress pad all the time. I wash sheets once a week, change the pillowcases every other day or so (think about what comes out your mouth, nose, scalp, face when you sleep. YUCK!) The dog is not allowed on any furniture, and not even allowed in our upstairs (sometimes he rebels) so pet hair is not an issue in our bedroom. I just like the feel emotionally during the day, and physically at night, of having my bed made.