We received a wedding invitation last year that asked that no children under age 18 be brought to the wedding "to avoid frightening the groom!!" We did not attend but thought it a silly request OR a real fear on the bride's parents' part that the groom might bolt at the last moment! We have not received any traditional wedding invitations in such a long time that I've almost forgotten what one looks like! One of the horrors of growing old . . . too many changes in too many ways and some of them so unbelievable!
At the risk of sounding like a killjoy, Etiquetteer really regrets the passing of the traditional, formal wedding invitation, written in third person from the parents of the bride and engraved (not printed!) by top-notch stationers like Tiffany & Co. and Crane's. A wedding is not Just Another Party. It's what Shakespeare used to refer to as a "solemnity," "a formal, dignified rite or ceremony," as in A Midsummer Night's Dream: "And then the Moon, like to a silver bow new bent in heaven, shall behold the night of our solemnities." The chain - uh, joining - of two souls for the remainder of their lives is not to be treated lightly.
Of course the formal forms have been necessarily adapted to today's blended families, and also to the reality of the Happy Couple being old enough to manage their own wedding all by themselves, thank you very much. Etiquetteer has become quite fond of the invitation that begins:
Together with their families,
Miss Dewy Freshness
Mr. Manley Firmness
request the honour of your presence, etc. etc.
Regarding the invitation you quoted, Etiquetteer has to wonder how much confusion it created with wedding guests who possessed children under the age of 18.
Joshing about one's Readiness for Marriage might be all right for the reception, but not for the invitation, and certainly not for a religious ceremony. But alas, Tradition is often seen as either Dull or Unoriginal or Both. Everyone is so busy being so Ostentatiously Different that we're forgetting That From Which We Wish to Differ.