Religions have never had a problem shifting away from "basic principles" across the ages. The obedience of slaves is a pretty core principle in early Christianity, and it is pretty clear that women should not speak in church. There will always be conservatives and orthdox members that dislike the change and point out the contradictions with the religious sources, but religious texts are almost always really vague, contradictory, and possible to spin to support almost any possible interpretation. Plus people start accepting what their leaders say after a while. So I get what you're saying that this is a big shift (and raise some inconvenient questions, e.g. if this is the truth, why did it take the church 2000 years to realize it? Will it change in the future again?), but it is business as usual for religious groups.
That's all very true, but I've never heard of a religion that kept its hold on the population by telling them that god accepts them even when they disobey. The entire principle of religious control comes down to guilt over sin, and that a god can make that right (through servitude).
What use does a person have for a god if there is no sin to forgive? Sin is the religious business model, and without that there's nothing left to sell.
Keeping with the business metaphor, religion has been losing market share in the wealthiest and most developed markets, so maybe they feel it is time to bring in a new VP of marketing and try to reach the millenial demographic. I don't think it will work, but they must be desparate to try anything given the immense risks that you point out and perhaps permanent damage to their brand and most loyal customers.
I'm not even catholic, but this pisses me off. Its not just acceptance. That would be truly christlike behavior. This is religious revisionism. If god is responsible for creating people to act the way they act, that will eventually be applied across the board. Musims and atheists, tyrants and serial killers, CEOs and politicians, all absolved of their actions in the eyes of the catholic god.
This is confusing because it removes all illusions that people are responsible for their actions. It's the most basic principle of christian theology. This pope is making sin obsolete. He's actually trying to kill his religion. WTF? Why?