Romo mentioned that both defenses were gassed going into overtime. The 49ers even more so, because the chiefs ended the 4th quarter with and 11 play scoring drive. So getting the ball first and allowing your defense a breather isn't a horrible idea.
You could also point to the49ers being the only group of people on the planet that did not know Mahommes was keeping it on that 4th down QB run for a first down. They lined up in shotgun...