Well, I don't agree with this approach: the only container that can be run in an embedded fashion is Jetty, and an embedded container's many parts are "polluted" by Maven's initialization (XML parser, various settings, ...).
Moreover, if you want to run tests on any complete container (JBoss, GlassFish, ...) or want to use, say, Xmx settings; you will need to use a standalone container.
But, we could add a "jetty-embedded" profile; for people who really want to use an embedded container. But, frankly speaking, I see no real-life use cases for the embedded container in Maven2. And, if we add it, we should add it in both archetypes.