In his article, "Push-Me-Pull-You: Reconciling Maintenance And New Releases", Jacques Murphy gives us guidance on when to emphasize maintenance of existing functionality (e.g. bug fixes) versus new product features. I think his treatment of the issue misses the point.
Many companies face this issue. Just about every product has bugs and seemingly marginal usability problems. Yet it can consume a lot of development resources to fix them. Meanwhile, the typical product also is in a marketplace which requires new functionality to compete effectively.
If you are an executive at a company facing this issue, make sure you have a product manager who simply sidesteps it. The important issue for a product manager is not maintenance versus features, it's what the product enables the customer to do.
Bugs prevent a product from meeting its requirements. Missing features prevent a product from satisfying its requirements. Focus on the requirements; ensure that product designers and developers have measurable criteria against which to measure their progress. Leave the decision of whether to fix a bug or implement a feature to them. If it's "better" to fix a bug, it's because it's the most efficient way to make progress towards satisfying the requirements. If it's "better" to implement a feature, it's because it's the most efficient way to make progress towards satisfying the requirements.