Software that's single-threaded, no it doesn't benefit from more cores
But - to an extent - running multiple single-threaded applications does. You're still bound by I/O, but it lets you do things like have something ripping a CD/DVD or doing a/v encoding running the background while you're still able to play a game online. In most cases add an Antivirus to the mix and it's quite often sucking up a good portion of a core when you're hitting a lot of files (again, also I/O, but SSD's help)
Most people wouldn't multi-task enough to see the advantage of 8 cores, but they used to naysay multi-core as well. Go back to a high-Mhz single-core machine and tell me it's not painful.