If all of part 2 is "must have" yet that is enough to significantly increase your satisfaction with the game, that's still a very significant find. Exactly the kind of things I want to test for.
It is, at least for me. I don't want every ending to be sappy-happy, but I do want one to exist, even if it will be devilishly hard to obtain.
As a statistician, however, I find that the psychological gap between "must have" and "irrelevant" is a tad too large.
"I would be happy if it's there, but I will not cry my eyes out if it's not" has to go in there somewhere. I know that gives a gut punch to ease of data processing and subsequent result representation, but it helps sift out "garbage data" of people for whom "irrelevant" isn't as irrelevant that settle for "must have" and vice versa. The gap between "detrimental" and "irrelevant" isn't as sharp, as I hope you will agree.