Not sure about Google Cloud Print, but many modern printers (mine’s an Epson) have wireless capability. I can print directly via WiFi from my computers, phones and tablets.
Google Cloud Print lets you print from anywhere you have an Internet connection. You can be on your laptop at the airport and send a printout to your printer at home or at the office, or to your client’s printer in Japan.
I get enough spam on my fax machine, so I'm not sure I would want the world printing to my printer too.