We once made a WP plugin for a project we've been experimenting with (called "webhome"). It was listed although it was half-done and was more like a proof of concept. It also sat there for a few years despite being incompatible with at least a few latest WP versions. Why? We just had no incentive to update it, or even look after our listing. If we were receiving at least $20/moth for it, we'd certainly give it more love.