@BuZz
You taught me that retropie_packages.sh trick, then I tried
sudo ~/RetroPie-Setup/retropie_packages.sh retroarch configure
And it created a configs/all/retroarch.cfg.rp-dist file. I compared (diff) it with my all/retroarch.cfg and found some few differences (input_state_slot_increase, input_state_slot_decrease, input_exit_emulator, input_enable_hotkey, input_menu_toggle, and some keyboard mappings for player1), but I think these differences are because I configured some keyboard inputs in emulationstation.
And then I tried
sudo ~/RetroPie-Setup/retropie_packages.sh lr-fceumm configure
And it created that small default retroarch.cfg for NES. I think this trick very useful to get the default system specifics retroarch.cfg. Is it OK to use this command for this purpose? (I mean: "can I suggest this command to the users that ask for how to get the default retroarch.cfg?")