FWIW, that is also the default behaviour of zsh's standard completion subsystem for kill. You can try it yourself: "zsh -f" to get a shell without reading a fancy config, start compinit, "kill <Tab>".

You can even disable verbose mode via zstyle, should you be the type of person that likes a simple pid list like bash's completion project provides. To me this level of customization is the main feature zsh provides, but not everyone incessantly turns every knob they see.