Sometimes if you want to set the watch to an exact second (if you're trying to time it to a reference time down to the second) it's just not possible without a hacking second. So then you have to wait for the whole watch to lose power. And then try from there. Overall, a lot of these big brands used to compete in 1950s and 1960s observatory trials. Back then all expensive brands had hacking seconds as this was a requirement for some tests.
A hacking seconds was kind of a requirement for a high end watch back in the day. A quick adjust DATE was another requirement for a high end watch back in the day. Kind of like how we've been programmed that there should be some wood flavors in any expensive wine. And now Harlan makes Promontory, a $1000 bottle of wine with zero % new oak barrels - it's a beautiful wine, but it really caught me off guard to not have a lot of wood notes. Then I started asking some questions and I realized it's made with 0% new oak. A generous friend had promised to pour a very expensive bottle of wine, and I was drinking it and not realizing it had been poured since I was expecting some wood notes.
Good to know the Breguet 7147 does not hack. THAT is a beautiful watch. I don't think my Patek Philippe hacks neither. I like my Patek Philippe, it's a beautiful watch - even if it doesn't hack. But still wished it hacked!
So, it's mildly annoying to not have a hacking seconds. Not a huge big deal. Not a deal breaker. But slightly annoyed if I'm trying to do some accuracy/performance test. Oh! My Octo Finissimo doesn't hack! If I ever get too annoyed by that in the Octo Finissimo, I'll let you know!!! Wink wink!
Our member, BluNotte, the Lange-Lover, he gets REALLY ANNOYED when watches don't hack. And he actively avoids buying watches that don't hack now. It's one of his first questions when he buys a watch - does it hack? If not, that's major negative points!