First I need to admit, that just mvn eclipse:eclipse studio:eclipse
won't ever run without an initial install, because modules do have
dependencies among themself. So go ahead and add the studio-plugin as
module if it works for you.
No, I don't think it's a good idea to build it each time.
It's documented (or will be) on the website and every Studio developer knows that we need to run mvn eclipse:eclipse studio:eclipse to generate the correct environment for work.
I think we can stay like that for the moment. No ?