There is this experiment with rats:
They got a rat into a jail and connected a cable to its brain, to a region where you get pleasure if you take controlled discharges. They connected the cable to a button inside the jail and let the rat discover its purpose. Of course, once the rat found how agreeable was pressing button the rat started using it quite often… naturally.
The scientists registered in a computer the patterns the rat followed clicking the button, and then they changed the experiment. Now they were going to provide pleasure automatically using this registered patterns, same cable, same discharges, same registered times. They predicted the rat was going to be as happy as before.
They were wrong.
Maybe happier? Neither. Actually the rat happened to be pretty stressed with the situation, looking nervously for a way to escape. So the scientists put another button in the jail, this time to stop the pleasure. As soon as the rat learned its purpose, it used the button to stop the pleasant discharges.
Why? The thing is that for basic functions like pleasure and rewarding our brain circuits depend on our active interaction. Our brain tends to averse to something if it just comes predefined.
Have you ever wondered why a child doesn’t feel comfortable in the perfect atmosphere designed by his/her parents? Have you ever wondered why a territory wants to get independent from a wealthy country? I’d recommend you to ask the rats, but only if you promise not to laugh at me.
[I read about this experiment in El Científico Curioso, by Francisco Mora, a book that I do recommend you — unfortunately I’m not sure there is an English version yet.]