The save to take half damage from a fireball strikes me as a rather silly way to model the effects of an explosion of any sort.
Instead of automatically hitting wherever you targeted, and the damage (relative to max) being determined by whether you somehow reflexively avoided half of the damage, a far more sensible approach would have the spellcaster perform some form of check to determine how accurately they placed the fireball, with damage (relative to max) determined by distance from the epicenter, combined with degree of cover (perhaps with reflex saves to allow movement away from the epicenter or towards cover).
As is, it produces nonsensical results like characters at the very limit of the effect potentially taking twice as much damage as those right at ground zero.