It's funny you should mention this!! Something I thought of earlier today actually answers this question!
First of all, I, personnally, have never been a wedding where any such a statement or even anything close to such a statement was made. I guess at the Black weddings I've been to, everybody knew everybody there was Black and no racial issues, comments or statements ever seemed necessary!
But, in answer to your query as to why such statements are or may be necessary, my answer is to look at it this way:
During a job hunting experience, I ran across the Houston Lawyers Association. This is not the same as the (Your state or town) Bar Association. This is an association of Black lawyers. In their mission statement, it states that at the time this association was formed, Black lawyers were not allowed into the Bar Association. So the formed their own. The same is true about all the flap a few years ago with the United Negro College Fund. Some White man legally protested and won an argument about there being such a Fund and the alleged discriminatory practices of it. But back in the day, the "Negro" could not even attend college, let alone be given money to do so!! So such a fund was a necessity.
Now, I actually said all that to say that there is nothing wrong with being Black in America ... or as being an American, and celebrating our own culture/heritage/achievements as a race. I actually believe I am offended by those who find falut with it! We are, after all, both Black and Americans!!! Are we not? As America (usually proudly) boasts as being a "melting pot" nation, there's obviously all kinds of people from all kinds of places here ... we are just one "kinds" of those people. We are Black people! And I don't see how or why there has to be a problem with us acknowledging that in any way! Why should someone else get offended about that? Why not instead celebrate their own heritage and culture!
Or is American all the they have??
Anyway, now, on to the American part of this equation. In this big 'ol "melting pot" of ours, Black people are the only
people who were brought here in chains! All others got the option to come here, and did so, for the proverbial, "better life", "safety from persecution", "land of the free, home of the brave" "better opportunity", blah, blah, blah. History dictates that the ancestors of most Europeans found their way here for one or other of the reasons stated above ... while most of our ancestors were brought here bound, captives and sold
to those European ancestors to be treated worse than animals!
Yet, White people want us to celebrate our Americanism in the same way they do, without regard or acknowledgement of our own unique experience as "Americans". I don't have a problem with waving the flag of freedom here in this country ... but, why should I also forget that when it was first hoisted, there was no freedom for me? Since my experience here is twofold, why should I not be able to celebrate or appreciate both experiences?
I know this is more answer than you bargained for with what seemed to be a simple "wedding" question!
But, as you ask why it seems to be "necessary" to invoke Blackness into a situation where it seemingly doesn't belong, the answer is that it DOES belong. And there is nothing wrong with it belonging. Being Black is relevant. It is important. As is the distinction of being a Black American. Our situation is unique. Special rules apply. Appreciation is a wonderful thing. Do those who discourage it do so because they have nothing to appreciate?
And on a more personal note ... I think anybody who's ever experienced love other than Black love would have to say that Black love is indeed at least a different kind of love than any other! And so "more beautiful, precious and/or rare" might just indeed apply!
But that's just my opinion!