It was pretty useful in my experience because sometimes the line you called was busy, sometimes a human answered instead of a computer, and sometimes a computer modem just didn’t pick up for whatever reason. Hearing the dial & handshake was a way to know what exactly went wrong when you weren’t able to connect. BBSs didn’t have this problem so much, but it happened often enough when modeming with friends or with small businesses that didn’t have a large modem bank and a lot of lines. Typing the wrong number was common. I also remember experimenting with robo-dialing with my childhood friends, calling through a list of numbers, like in War Games, looking for unknown computers to connect to.