Abe is not representing himself or his grandfather, father, mother etc....

He is coming as a representative who speaks on behalf of a country.  In this case a country that attacked  another country without first declaring war.

The bite they took was way to big for them to swallow. The Japanese were also to blame for the atomic bombs, because they refused to accept that defeat was inevitable.  They were too stubborn then, and, it seems too stubborn now, to apologize.  But really, Hiroshima and Nagasaki made a nation bow that previously refused to for reasons of pride, and therefore, were warranted.