In a weekly Torah sheet, Maran HaGaon HaRav Ovadia Yosef Shlita discusses the minhag of a choson breaking a glass at the conclusion of a chupah, lamenting the fact the custom has become amusing rather than reminding us of the destruction of the Beis HaMikdosh. The Rav states this significant minhag in the case of many bridegrooms has become nothing more than frivolity and a testimony to one’s strength, one’s ability to smash the glass in a single stroke.I'd really have to see the parsha sheet inside, because I am not certain what Rav Ovadiah Yosef means by "The choson smashes the glass into small fragments and the tzibur shouts “mazel tov” he writes, and the result is exactly the opposite of the intention of implementing the minhag". It would seem that he is saying that they are saying "mazal tov" and wishing congratulations on his ability to smash the glass, or at least are regarding the smashing of the glass as a sign of a good thing.
The choson smashes the glass into small fragments and the tzibur shouts “mazel tov” he writes, and the result is exactly the opposite of the intention of implementing the minhag. While the Rav states it would not be proper to eliminate the minhag, the actions of some compel one to think doing so might be preferable.
The Rav speaks of the minhag among sephardim, to recite “If I Forget Thee Oh Jerusalem…” while the cup is broken, suggesting the rabbi officiating at the chupah to instruct the choson to recite the posuk after breaking the glass, to enhance the significance of the act and to remind the guests of the symbolism surrounding the act.
The too-often-seen practice of jocularity and concentrating on the force exerted to smash the glass should be replaced by proper reflection of the churban and what the act, breaking the glass symbolizes.
But what is really happening there is that everyone sits quietly for the duration of the chuppa, for the kiddushin and the nisuin. And when the proceedings are finally over, everyone shouts "mazal tov!" for the completed marriage. And then they dance the chassan and kallah out, to the yichud room, to joyous music and dance. It just so happens that the last ritual under the chuppah is the breaking of the glass. And so the two are accidentally juxtaposed. But they aren't saying "mazal tov" for the breaking of the glass. (This, even though during the year, people do say "mazal tov" when someone accidentally breaks a plate.)
At my brother-in-law's wedding last week (mazal tov!), someone sang "Im Ishkachech Yerushalayim...", "If I forget thee, O Jerusalem" in the microphone as the chassan was breaking the glass. This is more or less in accordance with Rav Ovadiah Yosef's suggestion. Though it wasn't done because of Rav Yosef's prompting. Rather, I've seen this practice at many weddings in the past few years.
On the other hand, this may be a case of being darned if you do and darned if you don't. I recall that my rebbe for Yoreh Deah, Rabbi Weiss, was very much opposed to this "new" minhag of singing Im Eshkachech. This was not the way things had been done, and one should not innovate a minhag. (On the other hand, eventually klal Yisrael will continue with this new minhag long enough for it to become an old minhag.)
But assuming for the moment that this custom of smashing a glass indeed has lost its meaning, at least in the communities Rav Ovadiah Yosef is referencing, just how did this come about? The source for this wedding custom appears to be, initially, in Berachot daf 30b - 31a:
We learn it from here: Serve the Lord with fear and rejoice with trembling. What is meant by 'rejoice with trembling'? — R. Adda b. Mattena said in the name of Rab: In the place where there is rejoicing there should also be trembling. Abaye was sitting before Rabbah, who observed that he seemed very merry. He said: It is written, And rejoice with trembling? — He replied: I am putting on tefillin. R. Jeremiah was sitting before R. Zera who saw that he seemed very merry. He said to him: It is written, In all sorrow there is profit? — He replied: I am wearing tefillin. Mar the son of Rabina made a marriage feast for his son. He saw that the Rabbis were growing very merry,
so he brought a precious cup worth four hundred zuz and broke it before them, and they became serious. R. Ashi made a marriage feast for his son. He saw that the Rabbis were growing very merry, so he brought a cup of white crystal and broke it before them and they became serious. The Rabbis said to R. Hamnuna Zuti at the wedding of Mar the son of Rabina: please sing us something. He said to them: Alas for us that we are to die! They said to him: What shall we respond after you? He said to them: Where is the Torah and where is the mizwah that will shield us!It is not entirely clear, from the context of the gemara, that the reason for limiting the extreme merriment was specifically sorrow about the destruction of Yerushalayim and the Beis Hamikdash. (If so, saying or singing Im Eshkachech would not necessarily be the most meaningful here.) But regardless, this gemara would seem to be the source for breaking glass after nisuin. Indeed, this is what Tosafot says on the daf, מכאן נהגו לשבר זכוכית בנישואין.
But there is a difference between the gemara and our practice. Most obvious is that in the gemara, it was the father of the chassan, who was making the feast, who broke the glass.
But what I would consider an equally important distinction is that this was not planned. Mar bar Ravina, and Rav Ashi, did not necessarily plan in advance to break the glass, as part of the ceremony. And had the rabbis not grown so merry, they would not have violated bal tashchis to break a glass. This was a conscious decision, taken in response to a specific need. These Amoraim had the same response because one took his cue from the other, but still, it was only in response to the specific need.
In contrast, once this becomes unthinking minhag, its nature changes. It is not done with the same thought and deliberateness, but rather becomes part of the proceedings. They break the goblet even when people are not exceedingly merry, or in danger of becoming so. And since it becomes part of the proceedings, which is one of joy, it begins to lose its initial meaning, and develops new, positive, associations. It could readily become a celebratory act, much like the Greek practice of smashing plates in joy.
I would compare this to the Mishna in Avos:
רבי שמעון אומר, הוי זהיר בקריאת שמע [ ובתפלה ] .ש
וכשאתה מתפלל, אל תעש תפלתך קבע, אלא רחמים ותחנונים לפני המקום ברוך הוא, שנאמר (יואל ב) כי חנון ורחום הוא ארך אפים ורב חסד ונחם על הרעה.
ואל תהי רשע בפני עצמך.
The idea being that once it is fixed, it loses meaning. Of course, there is a fixed order and wording to Shemoneh Esrei, which Chazal established, and there is value to that -- and we are not supposed to deviate too much from it.
[At this point, insert homiletic lesson and praise of / blessings for Chassan and Kallah -- yes, I am trying to work this into a Sheva Brachos speech.]