I think there are definitely reforms that should take place.
I think primaries could stay, so that there’s some consensus by the public on who the party should nominate, but primaries should be open (not just for registered party members) and should take place on the same day nationwide. It would be more fair if we actually abolished the electoral college because it would truly give everyone equal power in deciding the outcome. (In solidly blue or red states, it can be disheartening to be outside of that major party.)
I agree on automatic voter registration at age 18. I would also like for people who were incarcerated to have their voting rights restored upon release. I think that exclusively mail-in balloting (like in Oregon) might improve voter turnout.
I just thought I’d mention that the 9% is actually 9% of people in the United States, not just eligible voters. It includes immigrants, children, unregistered voters, and felons who haven’t had their rights restored.