i think the choices in #nostr are not only technical, but social and mostly taken from the Bitcoin culture:
1. Open source and open protocol
2. Bips are Nips
3. transparency by default
4. selfhosting relays
5. all you need are your keys.
6. start with a small set of function
7. provide an emancipating tool
8. time it when twitter and co goes mental :) (like 2008 and financial sector)
TL;DR:
nostr reuses basic bitcoin culture to create a basic protocol that can evolve.