If you followed Larry's blog and articles, he also agrees that Multicam support missing is a big no no but at this point everyone believes that Apple will add it in the future, and it's not scrapped off from the application totally.
And no multicam support does not equal "this app is not a professional app".
Everyone knows FCP X is far from complete and Apple will be adding features to it with haste. As Larry says that "we'll all be using this thing in 18 months". Now 18 months is a long time for testing the app, but it also means that this app will deliver when Apple plugs the holes in that time.
Dot zero release not being ready for primetime have been said over and over since April demo, so anyone who thought about downloading it today and switching all workflow to it completely was dreaming at best.
Btw, length of usage obviously matters because it answers most of the "How do I do this?" questions.
And about merging the apps, it won't happen soon. It may happen way into the future, but I just don't see it happening. The idea behind apps like iMovie or iPhoto is that they are extremely simple to use because there isn't much to do on them. Once you start adding features, layman will be lost in it. That's why merging doesn't make sense.