Several folks have said here that it only took one disaster or near disaster to make them believers in straplocks. My experience was the opposite--it took only one near disaster to make me stop using them.
I had just slung on my bass and snapped the straplocks (Dunlop) into place. I was in a bit of a hurry, and I thought the upper lock clicked into place, but apparently it didn't. Since I had just taken my left hand off the neck, I managed to catch it with no damage done. This was certainly a user mistake, but hey, users make mistakes. OK, maybe I make more than my share.
I do maintain my strap pins and screws, and I use good solid straps. I also use Grolsch bottle gaskets except on my Kinal Kompact. The end pin on that one is also the jack, and it calls for a bigger hole in the strap. I modified one to fit tight, and I leave it on. I don't get acrobatic when I play, and my basses feel very secure. To remove a strap, I have to sit down and work with it for a few seconds.
Not trying to change anyone's mind, just offering a perspective. No straplocks for me (unless you count the beer-bottle gaskets).