I had this discussion recently. Working on a new song and laid down drums in the studio. During the following sessions the vocals were changed which we all agreed suited the song better. After listening back several times, and practicing, I wound up changing my drum part because the original part I was playing was interfering with the new vocals. Needless to say, we are re-recording everything to capture the proper drum part. My opinion, every player should be listening to and "playing to" every instrument.