Sure it would be awesome if every little change was tested backwards and forwards, and even 80% of bugs were ruthlessly hunted down and smashed (preferably with a can of Emoo's Fosters beer).
However, even AAA titles with literal armies of people can hardly manage such.
In Wurm one particular issue can be getting enough people to test things out voluntarily, let alone seeing how a change impacts live gameplay before going live.
I recommend utilizing the Challenge concept in this manner, especially for testing new pvp features. For example seeing how removing local list would actually play out instead of forum discussions with rampant speculation.
Players get a little something to help encourage testing, and the devs get a isolated, temporary, and accelerated sandbox to help get a better idea of how a change will impact live gameplay.