This is slightly off-topic, but I hope moxie (or an employee of WhisperSystems -...

This is slightly off-topic, but I hope moxie (or an employee of WhisperSystems - nothing official needed) wouldn't mind chiming in:

Since I loved the fact that I can run my own TextSecure server, I'm wondering why Signal does not run a similar model?

I'm curious which considerations went into this decision.