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.