Yes, such sentimentality would wash over Europe in the following centuries as Catholic and Protestant pietists and poets seemed to rival each other's bathos. I don't think the "mass persecutions" had a lot to do with it, but then I'm one that thinks the Middle Ages were mostly very pleasant and sensible times.
I'm of the opinion that in the pre-schism Roman days, when Rome was Orthodox and Holy, there was a slightly greater emphasis on the suffering of Christ, and I think a lot of this had to do with the persecutions of the Pagan Roman days and before there really was a specific canon of Scripture, and the Gospel of Mark being the prominent Gospel in Rome (as the Gospel of Mark is very succinct in the telling of the Gospel, but has the longest passion narrative - even compared to John). This slightly greater emphasis were seeds that, when separated from the rest of the Orthodox Christian world, blossomed into the over-emphasis we see in the Roman Catholic Church today.
I think it's why the "Lamb of God" (although the Agnus Dei hymn was added after the Quinisext Council, it seems that both ROCOR and Antioch are perfectly fine with that hymn) and the emphasis of the Eucharist being a "Sacrifice" is more pronounced in the Liturgy of Saint Gregory than it is in the Liturgy of Saint John Chrysostom.
However, with separation from the rest of the Orthodox Church, this slight liturgical emphasis gradually bloomed into the Franciscan spiritually and emotional sentimentalism present in the Roman hymns and artwork that we see today.
It's like how I view the ideas of the Immaculate Conception and Original Sin - it was a mistake / opinion by Saint Augustine (that is, inherited guilt) that gradually bloomed into dogmatic Roman facts when separated from the rest of the Orthodox Church and her Saints.
Or perhaps how the historical and venerable Roman tradition of Peter and Paul helping to found the Church of Rome, as well as her preserving of Orthodox dogma, got disfigured and deformed into the whole idea of Papal Supremacy and Papal Infallibility, proclaiming the Pope as the sole Vicar of Christ from the 13th century onward.
In the same way that these once Orthodox ideas which were distinct in the West got mutated into the Roman Catholic Church today, I think the emphasis on suffering was originally Orthodox - although, as you pointed out, certainly the rest of the Christ's life wasn't forgotten either as it seems now it is.
I think even with the Stations of the Cross, this same pattern of development occurred too. I believe that the Stations of the Cross originated pre-schism with pilgrims visiting the Holy Land and walking the path that Christ took, and pilgrims took that experience home with them; however, it eventually - very shortly post-schism - was integrated into the Roman Church as part of the liturgical life.
Although I don't mind heterodox ideas or even pagan ideas being "baptized" into the life of the Orthodox Church, as long as it teaches Truth and is consistent with the Orthodox Spirituality and Tradition (for example, I have no problem with Western Rite Orthodox using Fiddleback Chasubles or a Biretta, as both are beautiful and ornate and fulfill pretty much the same function that the Byzantine vestments do; they aren't much more variable to Greek vestments at least to me than the Russian Orthodox vestments are; Antioch allows both but ROCOR forbids both),

Compare that to
but I'm still curious as to how the Orthodox Church of Antioch (or ROCOR if they allow it) uses the Stations of the Cross.
If something like the Stabat Mater is Orthodox in its content, Glory be to God! I wouldn't want to remove something that is part of Living Tradition just because it's different. Nor, as Christ said, do I want to put heavy burdens on people without lifting my finger.
However, I can't help but raise an eyebrow, especially when I'm of the opinion - as Father Seraphim Rose of blessed memory stated - that the Roman Catholic Church as it exists now as an institution finished its transformation into the heterodoxy we see today by the 13th century, and its spirituality, ecclesiology, and traditions were unrecognizable to the Orthodox by that time, and this particular hymn which is a product of Franciscan spirituality (as it was written by a Friar or Pope Innocent III, the Pope that was friends with Francis and canonized him almost instantly after death) has some questionable lines of prayer in it that can be overtly sentimental.