> Just flip the sense of the option. E.g. turn `nondestructive?`
> (default #t) into `destructive?` (default #f).

I should have expressed myself more clearly: IMHO keyword arguments
should always be specified so that #f is a sensible default value for them.

If you feel like defining an argument that requires a fancy default
value, it's almost invariably a sign that you're being too clever. The
language-level restriction of #f actually forces you to design better
APIs. Common Lisp doesn't force it, and it encourages people to be too
clever in the name of pedantry, or simply because they can. When I
started out with CL I did the clever stuff a lot, but in the end I
dropped all of it and used `nil` default for all kw args without a
second thought. Life was simpler and better that way.

There's a usability book called Don't Make Me Think. I wish language
designers made me think less about the language :) Then I could think
more about the problem I'm solving. That's why I'm sympathetic to
Amirouche's point about lambda/kw adding more things to the language.