Core dumps can be useful if you know what to do with them. Some (most?) people don't, and just leave core dumps all over the file system. If you don't want them, making a quick change to your configuration files will get rid of them, but then again: most people are too lazy to do that.
One of my colleagues was one of those people. I got fed up with it when I realized his core dumps took almost half of the disk space on our file server. What to do?
When he went to lunch (without locking his workstation) I edited his .login, changed the default core dump directory to /dev/audio, made sure that the speaker volume was at the maximum and logged him out.
A few hours later he got a massive core dump, causing a couple of megs of data to be sent to the speaker, creating a noise like a collision between a steam engine and a truck full of pigs, lasting about thirty seconds.
When my colleague had recovered from his near death experience, he immediately set his default core dump size to zero...