Dear Tom,
Thank you for the feedback. I will share it with the OpenEI team. I think there was a change of policy regarding user participation in maintaining the database, but will confirm and get back to you when I learn more.
For now, you can keep your own database of tariffs to use with SAM. On the Electricity Rates page you can use the Save rate to file and Load rate from file buttons to create and use CSV files that store tariff data.
Best regards,
Paul.