Problem
Related to D15142
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.
D15142 addresses the issue for built-in exporters written in C, and this is meant to address the same issue for IO addons.

Solution
Change the use_selection property to default to true for each IO addon dealing with objects.

Old: Selected Only is off by default

New: Selected Only is on by default