Because it's a core Linux tool and they basically never change. Why doesn't ps have an option to only show your processes? Why doesn't objdump tell you what all the symbol flags mean so I don't have to look them up on StackOverflow every time?

I'm sure there are better examples but there are a ton of ways the usability of the Linux CLI could be improved but nobody is going to bother because everything's written in horrible C and to contribute you'd have to join some mailing list and convince a load of stuck-in-the-mud it-was-hard-for-me-so-I'm-not-making-it-easy-for-you neckbeards that your change won't break compatibility on a PDP-11, and anyway what's the problem? You just run `ps -fu $(whoami) | less`. Easy.

Way easier and more fun to write a new tool.