Griffith always cucked Guts starting in the Eclipse. I think this defeat was necessary so that Guts reaffirmed his resolve to stop Griffith and his demon empire. The pacing still seems excessively fast though.
Plus, Guts needs to somehow or other defeat the Godhand and the Idea of Evil in his lifetime since all people involved with Demonkind in some way (even victims like Vargas) are destined to go to Hell. Guts can have no true peace without defeating them.