My thought is that perhaps hotel chains/manager do this to set something of a "tone at the top" to remind employees to try to add a personal touch to employee interactions. When its set as a matter of policy at a hotel to leave a note for elite members (or anyone, for that matter) it may remind the employees to do the same.

When staying at a hotel recently in MEX I got a little note much like the one OP described, I'm certain they're printed out for all elite members. That same stay, though, the front desk staff remembered my kids, asked about one who was sick when they didn't see him for a few days, and offered a few other simple but kind gestures.

It wasn't the note that made a difference, but it did set the tone for the rest of the trip.