Why DOES there have to be a unified theory?
Because:
as below, so above. The cause and the manifestation have exactly the same nature...
If chaos and randomness do not feel good to live, do not make for an enjoyable life, then chaos and randomness are not the stuff of the universe.
If evolution -- moving from something known to something known better, experiencing a progression of perception as we go through our adventure on Earth -- if evolution is enjoyable and fulfilling and makes experiences easier, then evolution is what we should be looking for in the universe.
Don't forget:
universe =
unified.
There are no accidents, including with language...