Marathon UI is not actively maintained but we promised the community to at least accept bug fixes (so we should at least release the bugfixes). Also this is the only UI out there RIGHT NOW for MoMs and pure Marathon users.
We need to publish new release because there was bugfix by a community member and other community members are interested in that.
There was a build in TC that is deactivated.
There is new Jenkins pipeline for release https://jenkins.mesosphere.com/service/jenkins/view/Marathon/job/Marathon-UI/job/Marathon-ui/ but it does not contain maven deploy.
We will be able to update the Marathon UI in Marathon https://github.com/mesosphere/marathon/pull/6287/files
(there has to be an artifact on S3 for that to work)