They were (I believe). It's the "of course its not going to be the same" part that's OP just being a smart-ass. Only the first part of the sentence was needed.

Besides, even if they did know the show was cancelled, it still impacts how one views the show knowing one of it's major cast members is dead. Same with Matt Perry (Chandler) passing away recently - that knowledge will forever change Friends, despite the last season being in 2004.