responding to this post. You approach isn't very practical for personal use. There are often multiple people in a household and you may not mind sharing everything else on your laptop. If you think evernote has a limited use case and client set, then it's a whole different argument, but I don't think this makes sense either from a practical stand point. I think the benefits of adding a feature like this largely outweighs the cost.
I've really been looking forward to this feature as well. As I see the need to have more and more information on evernote, I think having a password/pin for the desktop is key as well. You've even added things like 2 factor authentication on the websites, so why not invest a bit more on security on laptops/desktops? Sounds like the weakest link.