When was the last time that you came across a printer with only a parallel port? Have you ever used one of those two serial ports on the back of your PC?
Personally I don’t think I’ve used a parallel port for over five years and I don’t recall ever having used a serial port despite using computers for over twenty years. So why do many PC manufacturers still include them on new PCs? Would they not be better using the same space for more USB ports, a Firewire socket or even to save a few pounds by simply not including it?