I’ve been convinced for a long time that simplicity is the most important property of a product. Long-gone are the 90s when a product was admired for its complexity. But I am also convinced that this is the most complex property to achieve and maintain as time passes by.
A good example of an over-complex product is Atlassian JIRA, a bug tracker that also do scrum management and plenty of other things via dozens of plugins. It’s basically a toolbox to create the bug tracker adapted to your company.
In my previous job, I faced an uncomfortable situation with JIRA because of its complexity. We used it for bug tracking and scrum management and I tried to upgrade our old version to the latest one. After some long hours to upgrade our setup on a test server, I finally got the latest version working but most of our installed plugins were not available anymore because the authors did not port their plugins to the new plugin API. Of course each plugin was there for a reason and I was in a tricky situation: keep the old version with security issues or upgrade to a new version without our plugins.
But it was far more vicious: There were about 10 versions between our old version and the latest one, and I didn’t find any of these versions working with our set of plugins! In the end, we were forced to keep our old version.
Atlassian forgot the most important lesson, even with a toolbox: simplicity! This is probably more expensive for them to keep plugin backward compatibility, but I would prefer for them to not have any plugin rather than breaking compatibility at each release. The final system is too complex to be maintainable and our final decision was to stop paying for JIRA support since we were blocked with an old release. It is even bad for their business.
You should be focused on simplicity for your users even it this results in more complexity for you (like maintaining backward compatibility)! As this post is strongly related to backward compatibility of API, I encourage you to reread this famous post of Jeol Spolsky: How microsoft lost the API war.