This is all your app is: a collection of tiny details.
-- Wil Shipley, founder of Delicious Monster
Regardless of how complete your vision is to begin with, it is the details which will make it cohesive or disconnected and ultimately a success or a failure.
Just because you recognize that details matter doesn't mean your decisions for those details will lead you where you want to go. No more so than sloshing paint on canvas will magically lead to beautiful art. Which is not to say it can't, just that it is unlikely.
To make something elegant, or useful, or [insert ambitiously positive success criteria here], you need to concern yourself with the minutia. Without all the tiny details; if you aren't obsessed with how they impact and affect each other, mediocrity is almost assured.