Ummmmmm, because scavenger hunts are fun???? And you could shepard drunk people to weird places on weekend nights??? So, I think I've scanned 2 QR cods in my life, so I understand they're failure. I think this is largely because they are almost always used to advertising or to get your contact info. Personally, I love them aesthetically as potential art media. (
http://knstrct.com/tag/qr-code-furniture/) (
http://annmortonaz.com/collectivecover_MyOMy.html). The same unknown destination thing exists with tiny links. I don't know if people are more likely to scan a QR code or type in a short / long url. What I like about QR codes in this context is that as text codes you wouldn't even need an internet connection - it really is like a coded message, which goes a long with the idea of a scavenger hunt. But yeah, something other than QR codes is a possibility.