The single most profitable thing that can be added to the server in my opinion is option to enable proximity voice chat in your phase.
For the server, it's free advertising, people will be able to make funny / interesting short clips and put them on youtube, like it's happening now in Rust (examples) or Dayz (examples)
For the players, it's richer d'n'd expirience, voice can express emotions a lot better than text, and it's faster.
Some people can say that text is more immersive, maybe, that's why it's an option not a forced requirement.
But i also think a lot of people used to regular d'n'd expirience with voice.
