Why does Mahasi Method have the points on the Body to attend to? What is the reason? It seems to be to train concentration while avoiding one pointedness?
Might the lack of one pointedness be counter productive at some point?
Any type of meditation that is worth the name will increase concentration in a beginner. 

The body is a good first object of vipassana meditation because it is inescapable and we identify with it so strongly, so automatically all kinds of thoughts also get faced.