I realize how upset you are with Princess in general, but identical situations have occurred on other cruise lines as well. Other than a reduction on your cruise fare & a letter of sympathy, I wouldn't be expecting much else. Friends of ours had the same thing happen on HAL a few years ago & hasn't cruised since. She had over 100 cruises in her life time & was also disgusted with how HAL had handled their situation. It can happen to any resort at any time but it does seem to be more concentrated aboard cruise ships. There hasn't been a cruise line who hasn't encountered the norovirus & according to the CDC "From 2002 to April, at least 101 cruises and 10,842 passengers had been hit by the virulent virus, according to the Centers for Disease Control and Prevention." Staying at home & not traveling at all seem to be the only other option to minimizing your exposure.
I hope you get some satisfaction from Princess as compensation but don't expect much else from any other cruise line either.