As Jack Campin said in the other discussion, being able to set out the text in ABC a readable way (though not neccessarily to play or sing from) with only a little more attention to character spacings is a big plus for me. Is that possible in LilyPond?

Another consideration is being able to make a start typing one-handed when writing down a tune learned by ear with instrument in hand. Typically I just put in the notes without worrying about octave or length, then go through and put the bar lines in, then sort out the lengths and octaves. So following the key signature by default is useful