I'm having trouble seeing any value whatsoever in wallet encryption.
Given the amount of computing power available to attackers (botnets, GPU mining farms, etc), you'd need to use scrypt parameters so onerous (multiple days on a regular PC) that there would be a significant chance of a single-bit error occurring during the calculations.
It's an offline wallet for one, so most of the security comes from the fact that it's pretty hard to steal. Second, it's the last line of defence. See my comment above about the time it takes to crack even a 5 character password. It's pretty significant. And lastly, what are the chances that 1: someone breaks into your house. 2: he finds your paper wallet, 3: he knows what it is, 4: he has a bot net / gpu mining farm to brute force it.