I don't think having the names recognizable is a sign of anything. If you look into the history of what are the iconic classic movies now, you'd see that it's not unusual to have people who are either relatively unknown or nothing special to come into one great movie and have a spectacular career afterwards. Great movie can launch an actor, but great actor alone can rarely save a bad movie.

I am much more concerned about show's creators attempts to "improve" Tolkien and turn it into a Platform(TM) for the Message(TM), instead of concentrating on telling a good story using the material Tolkien left us. That, unfortunately, is not an uncommon occurrence nowdays. If that happens, the series is doomed to mediocrity or worse, regardless of which names are attached to it or how much is spent on it.

Still, we obviously have to see it before making any judgement.