It will be easier for grandma if the key import/export feature would finally be pushed to the main client 
Then everybody can do this in a second.
Then everybody can do this in a second.
... and if it printed QR codes as well, with the ability to load them into a wallet in an automated fashion.
Trusting someone else to print you out wallet private keys is just insane - even if the OP of this thread is trustworthy, it sets a dangerous precedent allowing any asshole scammer to come along and repeat the trick.