Most applications don't need unconventional creativity though.

Most applications are years long projects that already have styling and code structure done by humans so if the mock up is not perfectly aligned it doesn't even matter because when you finally approve the design and get to building it; that's where the pixel perfect tweaking comes in. And again if it's a mature code base with an existing stylesheet it tends to come out with all the expectations you'd have of it because it's re-using components that already exist 99% of the time.