I would also like to have a better overview of the available modules. Some kind of catalog or App Store would be great. With a preview.
However, I know that it would be hard to implement this, as every module developer would be responsible to maintain their modules (incl. preview etc.) in this AppStore. However, many modules are no longer maintained. Whereby this could also be a chance to clean up with the legacy modules, because for many there are modern forks. The best example is MMM-PIR-Sensor.
And I could also imagine a quality ranking, not based on the amount of downloads, but on other metrics like user experience, usability and maintenance.