Some modules are just mature and stable enough and do what they're designed for, so they don't need more work/upgrades.
I can think off at least four scenarious where stable modules need maintenance/upgrades from time to time:
1. to fix notices/errors triggered by newer PHP/MySQL versions not released when the module was published
2. adpat modules to deal with core changes of newer WB releases (e.g. jQuery WB 2.8.0/1/2, referrer, CSS, ...)
3. update 3rd party packages delivered with the module (e.g. outdated PEAR packages, jQuery ColorBox plugin, ...)
So even I don't plan to add new features to my modules, it takes a certain amount of my time to test/upgrade them to work with newer PHP, WebsiteBaker or Browser versions, or to write documentation and answer questions in the support threads. In most cases people simply expect things run out of the box and don't care about things like: "created for WebsiteBaker 2.7" or requires "PHP 5.2 or lower".
You won't get much feedback/help on modules (even if you ask for) which do work, but a lot of feedback/requests in case something doesn't work as expected or you dare to rename your module to another name
Of course, there is always an exception to this rule