Rewarding maintainable code

In many software projects, developers are mainly rewarded for implementing new features. However, besides functionality, quality attributes like maintainability are also a key factor for staying competitive in the software industry. If the maintainability decreases over time, the cost for introducing new features will increase and in the worst case, the project will be unable to respond to new market demands in a timely manner.
In my opinion, developers should be explicitly and transparently rewarded for assuring the maintainability of the software, e.g. through refactorings or excellent technical design.
Unfortunately, the positive effect of new features is visible much earlier than the negative consequences of bad design or weak code quality. However, if we understand that investing in maintainability pays off on the long run, we could employ known methods for assessing the maintainbility of the software and reward developers for producing and sustaining maintainable code.