Yeah, I like the fact that we have four text channels, but I think almost every aircraft had options for up to four radio channels, also.
Four frequencies isn't much - but four separate COM radios is a lot even today More than 2 are pretty rare (though many modern ones can monitor a second frequency). More than one in WW2? Probably didn't happen too often.
Regarding the topic itself, +1.
Though it doesn't seem to be as simple as it sounds:
- If both TX/RX are switched, switching to air/ground only won't help being distracted by all people transmitting on "both"
- If it is a RX-only switch and TX is fixed by the type of vehicle, there is no way to get through with advice from one side to the other
This can only work nicely if full control over TX exists, but this requires everyone to use it appropriately. So it won't work nicely. Maybe, if TX doesn't have a "both" setting, it might enforce some proper use.
Given numbers these days, a country-all voice channel would probably work as well.