Why does Obama (against all past traditions) bow to foreign leaders?

Earlier the Obama administration denied bowing to the Saudi King, despite what the pictures showed.

"It wasn't a bow. He grasped his hand with two hands, and he's taller than King Abdullah," said an Obama aide, who spoke on the condition of anonymity. . . .

But this is something that he is doing consistently and it indicates that he is bowing to selected foreign leaders. As the LA Times notes:

This photo will get Democrat President Obama a lot of approving nods in Japan this weekend, especially among the older generation of Japanese who still pay attention to the royal family living in its downtown castle. Very low bows like this are a sign of great respect and deference to a superior. . . .

Of course, then the LA Times notes that there is the case of showing disrespect to the Queen of England.