Earlier quoted context omitted.
Does this already exist? Based on the top result I get from a Google search for 'maven copy file' [1] this seems to be not very well solved. The top response in that Stack Overflow page recommends calling out to a completely different build tool. It seems like part of the problem is that frequently you will have several plugins that each solve part of a problem but it is difficult to combine the plugins so they solve…
The stack overflow question is about copying files to a remote server during a build, not just copying a file to a directory. Use http://maven.apache.org/plugins/maven-resources-plugin/examp... — if your build copies files to a remote server you have other problems.
I know that Maven is ultimately capable of being used to copy a file. However, there are multiple ways to do this because all of the options have limitations and are somewhat awkward to use. For instance, I don't think resource plugin you linked to supports renaming as part of the copy.
Why is using your build to push files to a remote server a problem? A common use would be to deploy local code to an environment that simulates production. If that cannot be done as part of the build then it will exist as scripts that exist outside of the build. This means that there will probably be a lot more 'reinventing the wheel'.