> "abc" + "def" = "abcdef" vs "abc" . "def" = "abcdef"

Would be better comparison if you would use whitespace in the other case as well. Which then makes it just as readable.

Also. "0" + "42" would that be "042" or 42? It may be better readable, but the semantics are unclear.

That's an argument for types. While it's more convenient to use a language without types it's more error prone. So I guess in the end strong typing wins.

  >>> 0 + 42
  42
  >>> "0" + "42"
  '042'
  >>> "0" + 42
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
  TypeError: cannot concatenate 'str' and 'int' objects
  >>> int("0") + 42
  42