Many find paper money comforting and don't trust themselves using technology any more than necessary.
then let them use paper money. using bitcoin like this is like sending tcp ip packets per mail because you like the internet but its just "too online".
Yes, that is exactly my point. This will still require a Bitcoin Network transaction, but let the vendor worry about the geeky stuff. No matter how secure you make Bitcoin, it will be possible to scam some people with anything you design.
Paper based bitcoins really can only be used between trusted parties. In practice it seems to be heavily used to sell and give bitcoins to people that aren't set up yet to receive bitcoins. It makes for an excellent transitional medium (people are used to paper money).
Some just keep with paper (treating it as a long term investment), and some become part of the bitcoin economy. In either case it a valuable tool to introduce new users.
That said, if you walked up to me and I didn't know you enough to trust you and you were trying to buy something off of me with paper bitcoins, I would probably just import them directly before considering them mine. Of course, the amount of bitcoins in question makes a big difference. If it is less than $10 worth, I might just pocket it and call it good enough for now.