Let's look at the key question, which the OP also asks: "Why was ritual sacrifice so important in Mesoamerica?" (And why wasn't it in Europe?)
If we go back to ancient Mesopotamia and the Levant, we see greater tendencies towards human sacrifice. The Old Testament sees Abraham ready to sacrifice Isaac, showing that this wasn't just something for the per-monotheistic religions among the Semitic peoples. The concept lived on even when monotheism was already introduced. Nevertheless, it did subside. Concersely, it is believed that the Phoenicians (and their relartives, the Carthaginians) did engage in mass sacrifice of children. This is sometimes discarded as nothing but Roman propaganda, but the indications do point towards it having been very real (with the real question being: were these 'superfluous' children being discarded via sacrifice, or were 'valued' children offered to the gods). Ancient European societies also seem to have had human sacrifice, which later evolved into sacrificing animals and effigies of humans instead. Even animal sacrifice became ever more rare throughout the later stages of Antiquity (although there were some throw-backs).
In all European, Near-Asian and North African examples, the common pattern seems to have been that human sacrifice was something that was done under rather extreme conditions. It wasn't standard practice, it wasn't a fundamental part of the religious rite. It was what you did to stave off true disaster.
Now compare this to Meso-America. Why was human sacrifice so big there? Because it was standard practice there. Not something done in extreme times, but something done always, methodically. "Part of the routine". As far as I can tell, this was the case because the common belief was that such sacrifice was needed to preserve the world. The gods need human sacrifice, and withholding it would have apocalyptic consequences. The exact belief certainly varied from time to time and from place to place, but this midset was a general one in the region.
I suspect that it's the crucial difference. If you can introduce a European religion that successfully preaches that the world will end in some horrible way unless the human sacrifices keep coming... then you'll see something like the Meso-American practices mirrored in Europe. The further back you go in time, the closer you get to some kind of human sacrifice being accepted as 'normal'/acceptable. In a post-Roman context, it's going to be very tricky. I'm almost tempted to circle back to that notion of a Norse death-cult emerging, purely because the Norse societies did still have some notion of human sacrifice.
An idea, although pretty wild: just as the Christians really unleash their attempts to convert Northern Europe, and the pagans are beginning to feel the heat pretty badly, an ATL plague sweeps to Europe, causing Black Death-levels of death in the south of Europe. Some pagan figure in the north explains this as the old gods defending their people against the evil Christians. As the plague also spreads north, he advocates human sacrifice to prove loyalty to the gods. This is followed rather widely. The plague indeed hardly spreads in the northernmost parts of Europe (in reality because the colder climate is less suitable for the disease). From this sequence of events, we end up with a severely depopulated Christian Europe in the South, and a much less hard-hit pagan North. In that latter region, a new religious practice of human sacrifice emerges, perhaps rooted in a duty to wage war against 'unbelievers', and sacrifice the prosoners to the gods-- as a way to prove continued loyality, thus preserving "The Northern way of life". The general belief is that ceasing the sacrifices would cause the angered gods to let the Northern cultures be destroyed completely...