I think that there is a use of the negative emotion of disillusionment that you are missing. When you switch to a more negative belief about a person based on new information for example, simply thinking about them differently in the future is not enough to adjust your emotional relationship to what you now think is appropriate. The time you spent believing the positive lie still counts in their favor instinctually. The pain of disillusion corrects for that.
If Santa isn't real I want to retroactively cancel all of my fondness for him so that my history of believing in him can no longer influence me. That happening all at once hurts a lot. The motivating to face this pain is not just the desire for more knowledge. It has to be balanced by feeling an appropriate amount of fuzzies if my belief in Santa is confirmed by the experiment of pointing a hidden web cam at the fireplace. If we weren't loss averse they would cancel for the same reason you can only try to test hypotheses rather than to confirm them.
You can't try to be legitimately disillusioned or the opposite. You can only try to gain knowledge. So satisfied curiosity breaks the tie rather than replaces disillusionment.
I was meditating on the word "disillusionment" the other day, and it stuck me as odd that it has such a negative connotation... doesn't being disillusioned mean that you see a truth that was previously hidden from you by a mirage of falsehood? The human-universal negative emotional response to finding out you were wrong seems counterproductive in the extreme, and I'm still working towards eliminating it from my mind. So I crafted this brief litany, and I think that with some help from the LW community it could become a useful tool for rationalists, much like the Litanies of Tarski and Gendlin. My "first draft" is:
"If you love truth, learn to love finding out you were wrong. If you hate illusion, learn to love disillusionment. If your emotions are not appropriate to your values, do something about it!"
What say you?