Dumb questions: if BedRockDB has all of these huge benefits over using stock-SQLite, why hasn't SQLite merged in all of the changes into SQLite? Why does BedRockDB have to exist as a separate fork?
They intend to support it till 2050 - https://sqlite.org/lts.html - which includes keeping file format and API backwards compatibility. That accounts for the more careful decision making since things added now have to be supported for another 30 years.