Well I thought that the whole idea of the release plug-in was to avoid creating jobs (with separate workspace, triggers and other configuration) just for the tasks that happen few times in the life time of a branch, and therefore do not require a fully fledged Jenkins job.
And that's why I'd like to skip the normal build (which is something around mvn clean install) and instead in case of a release do a release build (sth around mvn release:prepare). I just feel it's more clear when I've got builds for all my branches that continuously verify that the branches are fine and within those builds I've got a button to make a release from this specific branch than to have 2 builds for every branch one for release & one for the standard CI build.
This is more or less what the m2release plug-in does, but this one does not offer special pre-/post-release actions that your plug-in offers.
If you were going to skip all regular build steps, then why not just create a new job called xxxx-release and use that just for releases?