1. To detect RSS feeds and show an icon in the UI
2. Render RSS files, so they look better than raw text
3. Link that UI icon to a subscribe function: Show a configurable list of RSS Readers and send the feed to the subscribe URL of the selected one.
This can already be added with extensions, but it would boost RSS adoption if it were a default feature. And thus support the official mission of Mozilla.
Would mozilla block it if a RSS advocate group would provide the development work to get this back into the browser? Is there a technical issue, like that there is no fitting RSS/XML parser that can be used?