The largest post-design cost risk for non-software products is manufacturing. This makes design for manufacturability is a major design driver.
The largest post-design cost risk for software products is maintenance. Unfortunately, design for maintainability is not the standard for software. People often ask what software maintenance is and they'll joke that you don't have to grease code. Well, you don't have to literally grease code but figuratively greasing code to ensure that it is easy and quick to change does need to happen.
For example, at my workplace Apache Ant was a primary build tool. It has been replaced with Gradle and as a consequence when development teams have to work on a service that is built with Ant they complain. The maintenance work here would be to change the build code from ANT to Gradle to ensure that work is easy and quick. Of course, whether to make that change depends on whether that service is getting modified often enough to justify the cost. The architectural question is was this service designed in such a way that changing the build code to use a different build tool easy. We approached this by ensuring that the service's build code was loosely coupled to the service source code.
A designer has the responsibility to select an optimal software architecture to satisfy the requirements. Obviously, the appropriateness of this architecture will have a profound effect on system performance. However, the selection of this architecture also has a profound effect on the maintainability of the final product. Specifically, architecture selection is more significant than algorithms or code as far as its effect on maintainability.
