Jump scares suck. They’re the most unimaginative and cheap scares ever. They can hardly even be called scares, they’re just surprises.
But they have their place. You’re right, it’s a surprise, not a scare, but when used right, they can get your heart pumpin’ and that can get your fear/excitement levels rising. It’s over used and misused, for sure, but I love a well made seat jumper.