I grew up with a C64 and a big part of the charm, for me, was the sound chip and the noises/music it made. I can understand why that chip has such a cult following.
Back then, when we had nowhere near the fidelity in graphics that we have today, these basic sound chips were used to add a lot of character to those early games.
Today you have high profile composers like Hans Zimmer doing work for video games and everything in a AAA title is generally very well produced, but I still find myself firing up some of the oldies every now and then. Nostalgia, I guess.