Can you explain what you mean when you say you ‘saw the reverence and solemnity… ebb away’?
Well, this took some thinking. In general, older practices and attitudes persisted for several years after the introduction of the new Mass, and new practices were adopted at different times in different parishes.
In 1970, we still received Holy Communion from a priest on the tongue, kneeling at the altar rail with an altar boy holding a paten under the chin.
The other priests in residence came out to assist in distributing Holy Communion. Now less value is placed on receiving from the hand of a priest. We have EMHCs that come forward to assist, even when there are so few worshippers that the use of EMHCs slows down Communion.
When Communion in the hand was introduced to our parish, we were instructed to step to the side after receiving the host and consume it immediately, while facing the altar and tabernacle. Even in introducing a novelty, some of the old careful attitude remained. And we did as we were instructed for a while, but over the years people started taking the Eucharist and then consuming while walking away from the EMHC. This makes it easier for abuses to occur (I found a host between the pages of a hymnal).
When a bow of the head before Communion was introduced, obviously some of the old attitude of reverence persisted, but not enough to make the new practice take hold. Most people here receive without making some sort of external sign of respect for our Lord.
Some parishes I visited experimented with hosts that tended to leave crumbs.
We used to genuflect every time we walked in front of the tabernacle (even if we were at a distance from it); now few of us do that.
IIRC, the lector used to genuflect toward the altar or tabernacle before reading. That was replaced by a deep bow, which in turn has been replaced by more shallow bows.
When the priest and altar servers processed out at the end of Mass, we genuflected for the crucifix and priest; that practice has disappeared.
We were taught to genuflect and cross ourselves if sprinkled with Holy Water during Mass. I don’t think people genuflect any more for the “rite of sprinkling”.
We used to maintain a prayerful quiet before and after Mass, until the '80s or '90s. If people spoke in Church, they spoke in whispers. Different parishes lost the quiet at different times.
We used to have votive candles before our statue of Mary & maybe elsewhere, part of the contemplative atmosphere that evaporated.
Other parishes lost more than candles, tossing out statues, icons and altar rails.
We had Mass both in the Church and in the school cafeteria. The cafeteria was noisier than the Church, especially after Mass, but people generally restrained themselves to a murmur until they got out into the hall after Mass.
Even in the cafeteria, where there were no kneelers, people would kneel for the consecration. We now have a kneelerless chapel instead of the cafeteria. The carpeting there is as soft as a kneeler, but far fewer people kneel there than kneeled on the linoleum in the cafeteria.
The flakier songs used to be restricted to the young people’s Masses. In the cafeteria, we told Michael and his sister to row their boat ashore, but in the “big church” we would still “Sing to Mary, pure and holy”. Somewhere along the way, even in the adult Masses, we started to try to “sing a new church into being” and pretend that we ourselves are the bread of life.
We had a problem for some years with homilies that were very thin on moral or doctrinal content. I’m not sure that all the priests I heard were blessed with a deep and abiding faith.
Early on, the priests at our parish always used Eucharistic prayer I (the “Roman canon”) and honored all the saints of the canon by name. I can’t remember the last time I heard Sts. Linus, Cletus, Clement and company explicitly honored in the new Mass.
There seems to be more of a problem in recent years of priests and deacons not strictly following the rubrics, but it may just be that I’m more aware of the rubrics.
Last year I sat behind a family that shared a snack shortly before they went up for Communion. That was new. But in general, things have been gradually improving around here for the last decade.
Almost all of the pious practices I remember are restored with old Mass, as much as circumstances permit. The changes go beyond Mass. Confession lines at our parish have become strikingly longer in the couple of years since the old Mass returned.