When using expect.toPass we have to pass a timeout value to each call and it's easy to forget. If the assertion fails, the runner has to wait for the overall test timeout (in our config this is 2 mins) before it will fail and potentially retry the test. Almost all our tests which use it have the same value, with only a small number that are set a little longer.
A global config value for expect.toPass would allow tests to fail more quickly should a specific value not be provided in a test, but could also be overridden at the suite, test or individual call level where more flexibility is required.