No, it has always been customary, its shameful that so many people were not taught the absolute basics.
I watched my grandparents and my parents do it growing up, and I do it and have taught my children to as well.
Common human decency tells you to show appreciation to those who do things for you. A hotel maid, unless it is someplace like Vegas, is a low paying position no matter how much the hotel room costs. IF someone is cleaning up your crap so you don’t have to, leaving a few dollars as a tip to thank them for it is just common sense.
I tend to only tip when they go above and beyond, or something I needed forced them to do more work. If I followed my dad’s customs, I would leave nothing, or would be arguing that the bill is too high when something is wrong in the room.