I don't see a problem if you create a branch first. The wiki page was created just to show people how to do a release, and not really to force them into that process. As long as the end result is the same, i.e. you have a tag and a reproducible build, changes/additions to the process like this are fine by me.
I don't understand why you want to branch first? You have a branch already (happens to be the trunk) and just want to tag subsequent releases on it (Beta1, Beta2, ...).
It's an optional step that isolates the codebase from forward-moving development changes, and (I find) eases the process of tagging Beta1, Beta2 without incrementing the version number (as Maven will prompt as a default).
Mostly, it's a matter of developer preference; I happen to find branching an essential organizational step as tagging off trunk I find confusing. I've been updating the Wiki page referenced in my original post as I employ this process for EJB3 External API and EJB3 Impl projects.
This thread is precisely for this debate. :)
I believe dealing with our build system/maven limitations (and trying to fix them) is a different thing than the branching strategy. In the way you suggest the number of branches explodes.
I'd normally go for the simplest solution, but maybe that's me.