Non-Lutherans don't know much about Lutheranism. Almost nothing, in fact.
If you were to ask a random group of individuals at the mall to tell you something about Lutheranism, here's some answers you'd likely get:
1. It's a German group.
2. It's a German church that let Hitler do what he did. (Yes, I know this has been roundly refuted, but people still believe it).
3. It's a church that ordains women. (True for the largest nominally Lutheran group in the US. And that's the one most people are familiar with, if they know anything about Lutherans at all).
4. It's a denominations, like Methodists or Baptists.
5. You'd probably get a Garrison Keillor, Lake Woebegone joke.
6. It's a group founded by Martin Luther King, Jr. (Don't laugh. I was told this by a kid -- probably 9 or 10 at the time -- who attended an LCMS church and was with me at an LCMS summer camp. I've since heard others older than him say it).
7. It's a church that doesn't believe the Bible.
8. It's a church where people aren't born-again.
Those who believe themselves confessional Lutherans will answer that a Lutheran is one who subscribes to the doctrinal teachings of the Book of Concord.
That's good. However, I would suspect that 9 out of 10 members of Lutheran congregations could not name 3 of the books in the Book of Concord. Outside of Lutheran congregations, 99% of people could not tell you what the Book of Concord is if their lives depended on it.
Confessionals imagine that "Lutheran" means confessional. But it doesn't. If it did, Lutherans would study and hold to the teachings of the Book of Concord.
Which brings up the question: can we seriously expect to draw in members when ideas such as the above are believed?
Folks often say, "We need to teach them." Which is true. The problem is that no one wants to be taught about the nuances of Lutheranism.
There is no confessional Lutheran church body in the US. There are isolated congregations and pastors that seek to hold to the Confessions.
But if there is no confessional church body in the US, what are we doing hindering what we are seeking to do by dragging the ball and chain of a "Lutheran" label around?