Goddammit Josh! ... It's not like they put it at the end of every season (or every chapter). Besides, of course everybody knew, but it was still the end of something, and they had us guessing what kind of "end" they were talking about. The same for this week's finale, "this is the end" as in the end of this miniseries? The "end of the world"? The "end" of one character? etcOK, but everybody knew that wasn't the end of the story. When you're writing a book, you don't put "The End" after every chapter.
...And since there's a always a positive side, this week we got Scully *and* Reyes. That's definitely a plus.