The Unix-Haters' Handbook (1994) wrote:
The novice Unix user is always surprised by Unix’s choice of command names. No amount of training on DOS or the Mac prepares one for the majestic beauty of cryptic two-letter command names such as cp, rm, and ls.
Those of us who used early 70s I/O devices suspect the degeneracy stems from the speed, reliability, and, most importantly, the keyboard of the ASR-33 Teletype, the common input/output device in those days. Unlike today’s keyboards, where the distance keys travel is based on feedback principles, and the only force necessary is that needed to close a micro-switch, keys on the Teletype (at least in memory) needed to travel over half an inch, and take the force necessary to run a small electric generator such as those found on bicycles. You could break your knuckles touch typing on those beasts.
If Dennis and Ken had a Selectric instead of a Teletype, we’d probably be typing “copy” and “remove” instead of “cp” and “rm.”
Proof again that technology limits our choices as often as it expands them. After more than two decades, what is the excuse for continuing this tradition? The implacable force of history,AKA existing code and books. If a vendor replaced rm by, say, remove, then every book describing Unix would no longer apply to its system, and every shell script that calls rm would also no longer apply. Such a vendor might as well stop implementing the POSIX standard while it was at it.
A century ago, fast typists were jamming their keyboards, so engineers designed the QWERTY keyboard to slow them down. Computer keyboards don’t jam, but we’re still living with QWERTY today. A century from now, the world will still be living with rm.
For more Unix-hating fun, consult your pineal gland, or these two links:
UHH in PDF format, and ESR's bleated riposte,
UUH Revisited from 2008.