As mentioned in http://sublimetext.userecho.com/topic/51669-save-asynchronously/ and http://sublimetext.userecho.com/topic/92465-save-file-should-occur-without-freezing-editor/, saving files over a remote connection can be slow and the editor locks up during a save, which means the editor could be unresponsive for a few seconds. This is a major annoyance for me lately as my current job requires me to work remotely.
Loading already happens asynchronously, so why shouldn't saving?
I must say, I support this! Saving is a major PITA, even with the current ST3.