The reformers wanted to do away with anything which might cause scandal to the Protestant mind. And they succeeded. There is nothing that the reformed churches have in them which is difficult for a Protestant to accept.
That being said, the bishops of then and now have taken the bait; hook, line, and sinker.
When vertical theology left the building (literally with Elvis in his film, Change of Habit) in favor of horizontal theology, the idea Catholicism went right along with it, for the most part. Oh sure, we keep some of the language, we keep some of the devotions, we keep some of the trappings, but by and large, the faithful lost faith.
How can I say that? Where are they? Churches are empty, the faithful stopped assisting at Holy Mass. Convents are empty, the nun's became radical feminists. Seminaries and rectories are empty, the priests have quit their vocation. And by quit, I mean quit. They had vocations to the priesthood, but the reformers talked them out of it and the bishops just let them go.
The reformers told the priests that they were no different than a Protestant minister. Not in so many words, but by their actions. They took the Mass away from the priest and put it in the hands of the faithful. They took the priesthood away and put it in the hands of the faithful. They took the churches away and put the people in their place. The role of the priest was reduced to that of presider.
I'll elaborate. When they changed the Mass, after Vatican Council II, the priest ceased to celebrate the Mass. He now presides over the assembly who celebrates. This is most evident in the Liturgy of the Word. Prior to the reforms, the priest did everything in the Mass of the Catechumens. He prayed the prayers at the foot, he prayed the confiteor, he prayed the kyrie, he prayed the gloria, he prayed the collect. Now all of those things are either optional or they have been taken over by the faithful save the praying of the collect, which is all the priest does in the entirety of the Liturgy of the Word. The priest, prior to the reforms proclaimed the epistle, the gradual/tract/alleluia, and gospel. After the reforms, the priest does none of that if there is a deacon and none of that save the reading of the gospel if there is no deacon.
Quite literally, the faithful have taken over the celebration of the Liturgy of the Word and the priest sits passively and allows it to happen. He is the President of those assembled. Nothing more. So, his role after the reforms was reduced from celebrating the Mass to presiding over the assembly. With the priest left with nothing to do and half of his role removed, is it any wonder they left? Quite literally the priest lost his identity and his vocation was lost, it was ripped away, like a teddy bear on the first day of school.
Secondly, they took the idea of ministerial priesthood and took that from the priest too. By a deliberate and exacting change, the royal priesthood was thrust into the role of ministerial priest. Laymen who had no business in the sanctuary were put there. They have been inserted into all phases of the Mass. And they have diminished the role of the priest, not only in the Liturgy of the Word, but also in the Liturgy of the Eucharist. They are EMHC's. They are commentators, They are ministers of the sick. They have literally invaded all of the roles which properly belong to the priest. Oh sure, the priest still consecrates the host and wine, but that is out of necessity. The rest of the Mass has been rendered optional for the ministerial priest and has been squarely put in the hands of the royal priesthood. There is a big difference. The role of the faithful is to worship. The role of the priest is to minister. Not vice versa. To thrust the faithful into the role of minister is to...well...Protestantize the Mass.
The Mass went from being celebrated at the altar to being presided from the chair. The altar of sacrifice has been lost to the assembly. The altar of sacrifice has been reduced to a mere table and the Sacrificial offering is now just a meal. The theology has changed. And it shows by the lack of faithful, the lack of priests, and the lack of religious.
The reformers vision has all but been accomplished. This can largely be contributed to two men. Paul VI and John Paul II. Paul the VI implemented the changes and John Paul II perpetuated them. It has fallen upon Benedict XVI to try and sort the liturgical mess.
We can talk about architecture, but architecture is just a symptom of a larger problem. And it is a visible symptom. The move from a Catholic theology with regard to the Mass (vertical) to a Protestant one (horizontal). There is nothing different between the modern Catholic churches and a Lutheran church or even a Methodist church. However, if you walk into a traddy chapel, it is clearly Catholic and it is very distinct.
My long winded point? Fix the architecture. But implore priests to fix the Mass. It is in their privy to do so.
Finally, I will say this. Which seminaries in the US are the fastest growing? Our Lady of Guadalupe in Denton, NE (FSSP) and St. Thomas Aquinas in Winona, MN (SSPX). Which orders of women are attracting vocations? (traditional and conservative orders such as the Nashville Dominicans). And which segment of the Mass is gaining the most attendance through growth each and every week? The TLM. It is no mystery. The Catholic faithful want to be Catholic, priests...let them be Catholic.