why?

This is a total rant - but why do restaurants mess with good recipes? Two of my favorite places have been toying with their recipes and in the process of messed them up.

I was at O'Charley's last week - I had not been there in forever and was very excited to get my favorite fried chicken salad with honey mustard dressing - got it, took a bite and they changed the dressing! BLAH! Made it so gross. Why O'Charley's? Why? Then I brought home another favorite - Guthrie's chicken fingers. Got home, took a bite of the cole slaw and BLAH! They changed the recipe. Why? Why mess with something good? So, you tell me - what restaurant has changed something that you love and totally messed it up?