1) why would the default be bad? Like, why ever would one make a default bad if there are non-bad options? Because it is not bad, it just chooses different adv

1) why would the default be bad? Like, why ever would one make a default bad if there are non-bad options? Because it is not bad, it just chooses different advantages and disadvantages. Right Alt could be configured to do regular Alt modifier, or could be configured to enter additional characters (Alt Gr - third/fourth level). The first case has advantage that Alt-based keyboard shortcuts on right side can be conveniently entered by one hand. That is why there are Shift, Control and Alt on both sides of keyboard. Second case has advantage that you can enter more characters, but entering rightside Alt-based shortcuts is more awkward. Conventionally, US keyboard uses the first approach (as there are less need for entering more characters), while many non-US keyboards use the second approach. Also, why Compose key is not accessible by default? Because there is no Compose key on common PC keyboard (in constrast to some old Unix keyboards). Therefore, Compose key need to 'steal' some existing key, which is problematic, because users expect existing keys to work as expected. I personally use Menu key as Compose key, but other users may have different expectations.