I'm not too sure about the firstbits thingie, having at least the full address on there might be useful for people not having smartphones to scan QR codes.

Also about QR codes, without a webcam or smartphone one actually has to do quite some work to actually get to the address/private key (take a picture with a digicam etc.) - having a (compressed) cleartext private key might be useful, also as a backup. While the current Bitcoin users might be more on the "techie" side, still a lot of people don't even get what QR codes are, think they are only links to web sites or some other stuff. Having human readable characters might take more space but create more trust and also have some benefits for "non-QR people".