I think in the next release of SMF you should include all the "Tips & Tricks" (http://www.simplemachines.org/community/index.php?topic=15899.0) as included features. So it's as simple as a click of a radio button & located in the admin area. IE: If I want a birthday's to show up on the calendar, It should be as simple as a click of a button instead of going to a file and manually entering it, It will save alot of time and headache.
For the work around of manually entering mods that doesn't install onto other themes other than the default theme. There should be a global code that will automatically apply the mod to all themes.
Themes can be very different, and that makes it almost impossible to automatically install mods for all themes.
And implementing the Tips and Tricks in the admin panel will be a lot of work, and most people won't use these features.
And btw: no need the edit files to show birthdays on the calendar. It's just an option in "Calendar Settings".