While Biblical genealogies are not terrible exciting they are included in the scriptural texts for a reason.  This is certainly true in the gospels.  In addressing a primarily Jewish Audience the gospel of Matthew begins by presenting Jesus as both a descendant of Abraham and a descendant of David.  As such he is qualified to be the one in whom God's promises and purposes revealed to both Abraham and David can be revealed.  Both were important parts of the messianic hope.