It’s very difficult to get it right the first time, so it makes sense to spend more energy polishing your products.
The old truism for software projects in big corporations was that 75% of a project's technology cost is maintenance. In the world of tech startups, where a product that stops being developed is a product that's on the (sometimes slow) way to the graveyard, you can replace maintenance with polish, and change the 75% to 90% or even 95%, if your MVP is minimal enough.
This is one of the reasons why outsourcing rarely works for long-term product development. Working with a vendor who has other priorities is rarely a great way to add polish. You need the person in charge of putting the technology together to care about the polish.