Because Morita has power to take that center position and it proof it she can center keyaki song, i don't think matsuda and tamura can bring this song as energetic as morita did
藤吉 is 15cm taller than 森田. But, 村井 is only 5cm taller than 山下. It will be harder for 村井 to hold 山下 flying like 藤吉 holding 森田. It is certainly interesting to see whether or not 山下 can dance like 森田. 森田 is the best to perform this dance.