Hi, Current udev (post 168) have more use flags, by default flag keymap is not enabled. After update I found that my laptop Fn+ keys does not work as they used, kernel log had info about using setkeycodes to fix it. I found that keymap useflag fix it. So here's question - why do not enable keymap by default? I do not really see any advantage of udev without such default-flag, people will ran into problems.
It is already enabled by the desktop profile: # grep -r keymap /usr/portage/profiles/ /usr/portage/profiles/targets/desktop/package.use:sys-fs/udev extras gudev hwdb keymap If you are not running a desktop system, the flag does nothing useful. If you are running a desktop system and don't use the desktop profile, then you need to manage more than just the keymap USE flag.
I agree with comment #1. We can't enable this by default everywhere because it will bring in dependencies which are unnecessary for a minimal system.