Similarly there are still plenty of microphones that look like that, they're professional microphones, not "old fashioned" ones.
What's the alternative, pick something abstract that confuses people. That didn't work out so well for the recent GMail redesign.
It's thousands of years old, thus despite our ability to record and learn from history, we should replace it with something more modern.
It doesn't really matter as long as it's roughly ubiquitous, which the floppy drive is. It doesn't even matter if no one's seen a floppy drive; if someone doesn't recognize what the floppy icon does, then the rest of their computer is new to them and they're learning. Once learned, forget about it.
Etc.
And crashed beige boxes for Windows machines mounted on Macs: http://www.blogcdn.com/www.engadget.com/media/2007/10/generi.... :-)