The difference between considered work and generic work is rarely one big thing. It is a thousand small things that, individually, feel optional. Together, they are the entire product.
The thousand decisions
The kerning of the wordmark. The exact pink of the accent. The line-height of the body copy. The way a button responds to hover. The radius on the corners. The weight of the divider lines. The pace of the boot animation. The microcopy in the empty state. The order of the navigation items.
Any one of these can be defaulted. Default all of them and you have a generic product. Decide each one, deliberately, and you have a brand.
Why most people skip the details
Because the details don't have a clear ROI. You cannot point at the kerning and say "this generated $X." You can only point at the whole, after the fact, and recognize that the whole would not have felt the way it does if any of the small decisions had been defaulted.
The work that lasts is the work where the maker decided everything. Even the things nobody noticed. Especially the things nobody noticed.