You're right, this is a real issue. It's frustrating to spent time researching plugins when so many of the plugins I click on haven't been updated in over 2 years, it wastes a lot of time and makes it harder to find the right plugin. It would be good if the plugin repository on WordPress.org had a better search with the ability to filter out sort the results by date updated, rating etc. I would also like to see plugins being removed from the repository if they're not updated for 2 years, as other commenters have said. That would fix the problem immediately, encourage plugin developers to continue supporting their free plugins and leave hair which will encourage other developers to fork or replace older plugins that are no longer supported.