My installation process for a new mouse is as follows:
1 - Attempt to plug it in.
2 - Flip the USB connector.
3 - Plug it in.
4 - Use the mouse.
Is there anything at all to be gained from installing the software that comes with the mouse? Even with extra side buttons, I've never had anything not work out of the box.
Lights, dpi configuration, polling rate settings, surface calibration, and (as you mentioned) button remapping. Yes it will work without that but it can work better (and personally that’s worth a little extra ram anyways)