Ah, therein lies the rub.
I assume you've seen a lot of examples that constitute bad jumpscares, and so have I (flying naked guys *cough*) and I understand your attitude. But, only because there are bad jumpscares out there, doesn't mean all jumpscares are bad.
IMHO, it's a very good technique of implementing fear, but it has to be done ever so subtly and carefully to achieve its effect, what many CS creators seem to forget.
E.g. the skulls falling out of the desk in Study (yes, this is considered a jumpscare, skip to 14:46)
It was so finely done, and notice how it made sense in the environment. Moreover, it also served as some kind of a punishment for the player for their curiosity. It also provides a glimpse into what Alexander did to people, the details later explained in the notes.
On the other hand, the encounter in the Morgue is such a brutal and loud scare, yet I didn't mind, when the game decided to remind me of what lurks about in the castle all the time.
None of them broke the immersion for me, they added to it. I don't like being startled, when there's no reason for it. Overall, I just always give them a chance.