Even if the distinction between mortal and venial sin is found only in Catholicism (not just Roman Catholicism; there are also Eastern Catholic Churches who are in full communion with Rome), this does not prove that the distinction is theologically incorrect. First of all, in regard to faith and morality, the majority in the world is often wrong. Secondly, this doctrine is perfectly Biblical as well. “If anyone sees his brother sinning, if the sin is not deadly, he should pray to God and he will give him life. This is only for those whose sin is not deadly. There is such a thing as deadly sin, about which I do not say that you should pray” (1 John 5:16).
The Church does not use scare tactics for people to obey. Even excommunication is not a scare tactic. However, people who have an inadequate understanding of the faith will misinterpret this and believe that God is some angry distant being that just waits for us to mess us. Even since Adam and Eve sinned, people have been afraid of God and running away from Him.
The Church did not expand in the first century by preaching fear. Read the Acts of the Apostles. Did the apostles go around threatening people with eternal damnation? No; when they did mention damnation, they were simply making people aware of an objective truth. They weren’t threatening. Even God doesn’t try to control us in this way; he ultimately gives us the choice to accept Him or reject Him. He doesn’t send us to hell; we choose it for ourselves.
If you think of mortal sin in the way you do, then you are ironically underestimating the gravity of mortal sin. There are conditions involved, and even if only one is not met, there is no mortal sin. It’s actually more difficult to commit a mortal sin than most people realize.
The Catholic Church’s “interpretation” of God and morality is the only fully correct one in the world. Period. Moral relativism is not an option, and dogma can’t be changed even by the pope.
You said: “But it makes sense seeing how to not die in mortal sin is the end goal of Catholicism.”
No, this is not true; the end goal, so to speak, is to know, love, and serve the Lord. And if you honestly try to do that, then it is impossible to commit mortal sin. Period.