You're talking as if better estimation were an end in itself. It's not. The goal is a successful business. There's no point in spending any more effort on estimation than is needed to support the planning required to make the business a success; any more effort than that is simply wasted.
If the expected ROI on a project is small, then having really good estimates matters a lot, because it can make the difference between profit and loss. But if the expected ROI is large, precise estimates matter less. Tom DeMarco has famously made this point .