Instead of having to go into the pavu controls. It would be nice if we had the option to click the volume indicator in the panel and have all of our sounds per app right there. Maybe it is already there with a setting change?
Presumably you mean this volume control indicator (as there's two versions):
This would have to be a feature request upstream to the maintainers. Bear in mind by design, it's intended to be a simple menu for adjusting the main volume and start/stopping playback. A change upstream would also impact other flavours/Ubuntu distros, too.
That said, nothing is stopping someone from forking the code and making the modifications themselves.
Alternately...
MATE Volume Control has the options for per-app volume control. You can get to this screen in 3 clicks by clicking the 
indicator, clicking Sound Preferences and then the Applications tab:
If you create a launcher on the panel, you could actually get to this screen in just one click using this command:
mate-volume-control --page=applicationsWhat i find myself doing even more then per app volume is switching apps to different outputs. CSGO keeps reverting to my speakers and I prefer them to remeber where they were last. As if pavucontrol had its own applet