I don't think that CGI has killed our suspension of disbelief. In movies where it is done well or not overly used, CGI can make it easier for us to suspend our disbelief, making the scene look more realistic. Really, a giant killer ape looks more realistic as a computer generated image then it does as a clay figure or a man in a suit.
Too often however the CGI is too shiny or sticks out too much from it's real surroundings. If, like in Star Wars, everything is CGI and digital, then it actually is good. But in some movies, mediocre CGI just distracts you.
When you see something in a movie for the first time, you shouldn't immediately be saying "Oh, that's CGI", but instead noticing the action or the character. Too often the CGI is overpowering and distracting.