At least one reason for it seems straightforward, though. Whether something is important is a judgment that you have to make, and it’s not an easy one; it’s certainly not obvious what things are important, and you can’t ever be totally certain that you’ve judged importance correctly (and importance of things can change over time, etc.). On the other hand, whether something is interesting (to you!) is just a fact, available to you directly; it’s possible to deceive yourself about whether something’s interesting to you, but not easy… certainly the default is that you just know whether you find something interesting or not.
In other words, self-deception about what’s important is just structurally much more likely than self-deception about what’s interesting.
I agree with this, based on my experience.
At least one reason for it seems straightforward, though. Whether something is important is a judgment that you have to make, and it’s not an easy one; it’s certainly not obvious what things are important, and you can’t ever be totally certain that you’ve judged importance correctly (and importance of things can change over time, etc.). On the other hand, whether something is interesting (to you!) is just a fact, available to you directly; it’s possible to deceive yourself about whether something’s interesting to you, but not easy… certainly the default is that you just know whether you find something interesting or not.
In other words, self-deception about what’s important is just structurally much more likely than self-deception about what’s interesting.