Because after the end of civilization, you may be inputting your first programs on punch cards or something similar, and your system's memory capacity might be measured in a few kilobytes, not gigabytes. Compactness is a huge deal in this context.
Having spent a couple of hours as a kid typing in a https://en.wikipedia.org/wiki/SpeedScript binary printed in a magazine, one byte at a time, I can confirm that compactness is valuable.
