Problem
When exporting objects, it is common to only want to export the objects you have selected. However, the "Selected Only" option is false by default, which adds an extra step every time you want to export objects in a new file. Since exporting individual or specific objects is more common than exporting a whole scene, it would make sense to change the default value to true.
Solution
Change "export_selected_objects" parameter to true for each exporter, so "Selected Only" defaults to true.
Old: Selected Only is off by default
New: Selected Only is on by default
Limitations:
The default "Selected Only" value would have to be updated to true separately for each addon to maintain consistancy.