As a means of increasing the participation of the congregation in the celebration of Mass, recognizing that joining in chant is not possible at a Mass that is "read" rather than sung, in 1958 Pius approved the use of hymns in the vernacular at appropriate points in the service.[4] As a means to closer awareness by the congregation he also allowed the epistle and gospel to be read aloud by a layman while the celebrant read them quietly in Latin.[5]

We did this all the time at our traditional chapel (independent) growing up.
The priest had to drive to about 5 places on Sunday, so he tried to maximize efficiency. That was his only motivation.
Crisis in the Church. Priest shortage.

But frankly, I think we have bigger fish to fry than complaining about parallel readings. Replacing the readings with vernacular altogether, however, is literally the 1965 Mass.

Nevertheless, if ditching the Latin readings in favor of Vernacular had been the ONLY change after Vatican II, I would 100% certainly be attending my local parish right now. I can't even *imagine* how that alone would destroy one's Faith, even after many decades.

But that is just academic. Practically speaking, yes, moving towards the Novus Ordo is a highly alarming thing.

Yes, the Novus Ordo "did what it did" plus it got rid of Latin readings in favor of the vernacular. That's like saying a man did a mass shew-ting at a sch00l, and he was also impolite to several people on the way in. Um yeah, I guess he was impolite to a few people at the front entrance, but the real issue is what he did afterward...

So, as long as the priest is actually reading the Gospel, there's no strict issue liturgically, since the layman reading up front is no more a liturgical action than someone's child talking in the front pew, or even back pew.

I would certainly remove said "reader" from the sanctuary, and there may be confusion of the faithful regarding the non-liturgical nature of the action that perhaps certain practical measures can be taken to alleviate.  I've argued before for making Minor Orders permanent, and so this would be a case where you'd confer the Minor Order of Lector on the individual(s) who would do the readings, and this would safeguard Catholic liturgical theology from any slide toward Novus Ordism.

Whether it's vernarcular or Latin, IMO, is less the issue Liturgically than WHO is doing it.  As you said, Matthew, if the priest just read the Epistle / Gospel in English and no other changes occurred, it would be no big deal.

With all that said, in this day and age, most people have MISSALS and, unlike in earlier times in history, paper and books and printing are NOT EXPENSIVE -- and MOST PEOPLE these days are LITERATE and can read.  These factors take away all justification for this practice.  How difficult would it be to just have a one-page printout, perhaps added to the bulletin with the Latin + English and have the faithful just follow along?  And that would be just for those who didn't have Missals.  You could even just post it on the chapel website if you didn't want to spend the $5 to print out 100 copies of it.  In addition, comparing the Latin and English side by side might help the faithful absorb a bit of Latin over time.  My dad dropped out of school after 4th grade, since they were poor and he had to work, but as an adult, he knew what pretty much every word in the Latin meant (without obviously understanding the precise syntax) ... just by following along.

Finaly analysis ... there's absolutely no need for it in this day and age.  Sure, if printing and paper were prohibitively expensive, and if a significant number of people were illiterate, then maybe.  IMO, the only reason to introduce these practices, then, absent any practical justification ... would be to boil the frog toward Novus Ordism.  If the faithful get used to layman reading the Gospel, then it's one small stept to have layman reading it INSTEAD of priest, while priest and other clerics sit there listening.  From there it's anything goes in the Liturgy.

Replacing the readings with vernacular altogether, however, is literally the 1965 Mass.

Not so. I have a 1962 -- NOT 1964/65 -- ALTAR missal that has vernacular only for the Introit, Epistle, Gradual/Tract/Alleluia/Sequence, Gospel, Offertory, and Communion. It was clearly creeping earlier than the Council years.