Gents, before we get into an engineer's vs pilots switch responsibilities, it should be noted that for the most part maintenance manual procedures are just that.
I.E they are procedures written for us maintainers to use, and very often are written with our safety in mind, hence switches do get left in positions other than normal operating position.
For example, we generally do not leave ground spoilers armed, but pilots do,
we do not leave thrust reversers armed, but pilots do. I could go on, but as others have said, ultimately the flight crew are responsible for doing their checks.