The only people who need to train for shape are those who are already as big as they want to be. 99% of trainees aren't even close, and for them it is a good way to bring their progress to a screeching halt.
I don't get it either! Are the 2 mutually exclusive?
If I train to make my biceps bigger, or I train to make my biceps stronger... how would that alter the training that I did????
Or is 'training for shape' merely a reference to keeping symmetry in mind when training? Symmetry is important aesthetically, but it's important athletically too... muscular imbalances can lead to injury & problems, in addition to looking silly.