Sometimes I criticize some Protestants for being too “big picture” in their faith — e.g., if a Protestant feels that how you act in your day-to-day life is irrelevant because he’s “already been saved” and therefore doesn’t have to be nice to strangers, welcome the poor, help the sick, etc.
Some Catholics, on the other hand, sometimes get too “small picture” in their faith. Where that Protestant is looking only at the forest and missing out on the trees, we’re looking only at the trees and missing out on the forest. We get caught up in “the rules” and miss out on the reason they exist.
The correct response to God is in the middle between those two tendencies: yes, as you suggest in your post, we should remember the big picture — God became man and died for our sins, hallelujah! — while also remembering the little things (as Scripture reminds us, it’s wrong to celebrate God and then merely tell the poor “Goodbye and good luck! Keep warm and well-fed!” without actually doing something about it).
As humans, we have a tendency to want to know “the rules” so we can know what we need to do. This is true in our secular lives as well as in our spiritual lives, but sometimes it’s more obvious in our spiritual quest. “Good teacher, what must I do to inherit eternal life?” We want rules we can follow, and we tell ourselves that all we have to do is follow them.
The true answer in Catholic theology, however, is that it isn’t about following “the rules.” God isn’t a bureaucrat. We have to live the faith, which means that we have to stand on our own two feet and be responsible for our own decisions. That’s actually really hard. So we default to the fail-safe: we ask what the rules are and we try to follow them.
I got long-winded again. Sorry. Hope this helps.