SMFs are very important if you have to play songs that the piano is up front... playing with just one hand doesn't cut it.... Then, if you wish to use the bender extensively on a song, forget about arranger play...... If you wish to play a secondary instrument (trombone, in my case!) forget arranger play....

Mind you, all of the above situations would be possible on an arranger if they just brought back the f-ing CHORD SEQUENCER....!