Second Life regions have the follwing environment variables already, however they are read only:-
chat_range
,
whisper_range
and
shout_range
.
I think that it would be great if private region owners were able to adjust these values. For example, the ability to make chat effectively global would be useful in collaborative environments and games/experiences.
Likewise, the ability to make chat distance shorter may increase the utility of space.
Residents buy private regions to carry out their own vision - The more flexible private regions are, the more value they present and the more likely a resident is to buy a region.
I think that since these values are already environment variables, it would be a relatively quick win to make them writable if the region is not a mainland region.