isn't that just so that you've a large surface area mating together to prevent leaks?
the pressure your brake lines are at, would force fluid up the threads if there weren't something at the bottom of the thread for the brake line to bottom out on.
i've got a GTR brembo on my desk here that i've just took a look at.... and, if it works for them, then it's ok with me, if brembo don't know what they're doing.....we've no hope at all! HAHA