Turning arbitrary data into sound or pictures can be an easy way of getting insight into it, because human brains are so good at picking out patterns in those forms. It can also be fun, as seen in Doug McIlroy's talk about the history of computing at Bell Labs:
It was customary for computer operators, for the benefit of computer operators, to put a loudspeaker on the low bit of some register on the machine, and normally the operator would just hear kind of white noise. But if you got into a loop, suddenly the machine would scream, and this signal could be used to the operator "oh the machines in a loop. Go stop it and go on to the next job." I remember feeding them an Ackermann's function routine once.
These days registers change a bit too fast for that. But I still like to listen in on a machine. I listen to the disk rattle, and miss it when I'm using a remote machine. I often wish I had something more informative to listen to or look at. Not predigested data like the CPU graph. Just raw data, so I can accidentally notice what's going on, without having to think about it. Page faults, system calls, memory allocation, stack height - things that vary with what the machine is doing, but not in any simple way. Things best interpreted not by conscious thought, but by unconscious pattern recognition, because you have hardware for that.