What I meant to say was...and have posted before, is that for all the positive things that loyalty programs do for a guest, they also make the guest more willing to accept things as they are, sometimes good sometimes bad in terms of stays.
As pluto77 said it might be the anticipation of getting something to which we have become inured, or it might simply be our anchoring bias: We have been treated in the past and that becomes the new normal for us. In reality we cannot expect 100% gratification from any stay, or every stay. Thus our approach to loyalty infers an unrealistic expectation. That's what I meant by corrosive.
If there were no loyalty programs we would pay for a room and get we paid for--period! How boring that would be. As a good friend who ran security for a major gaming operation once told me--"we build these places to generate revenue from the hopeful losers, of which there are many."
But in terms of hotel stays, hope springs eternal--even though reality does not always cooperate.