Pluggable Feed Format
Sometime yesterday Jay Young's default feed switched back to RSS 2.0. The world didn’t end, and not everybody cares about such minutia, but Jay clearly does. Jay may be a minority, but this enhancement would enable Jay and others like him to simply drop in a plugin such as this one, activate it, and be on their way.
The patch does not change the default feed format from RSS 2.0. Perhaps that could be considered for a release like WordPress 4.0, and a plugin could be provided at that time to enable users to select the venerable RSS 2.0 feed format, but in any case such a change would require a separate ticket, as this patch does not do that.