If you're adding a site for accessing a cloud location with an unusually long user id or password (or God forbid an S3 Access key ID and Secret access key!), I would think a PIN required to use the site definition would be helpful instead of leaving out and having to retype the actual password or secret access ky every time. If a user is on your PC and wanders into WinSCP, you don't want them accessing a site just by clicking the site defintion...