The "poor" save progression is 1/3 level. Why not start there for everyone? I suppose the answer is because spell DC increases by one for each spell level, which is 1/2 caster level.
Dragonchess - I see that two levels each of fighter and barbarian add up to +6 Fort; how is that "in place of" +2 Ref +1 Will? As I see it, four previous levels of Ranger instead of 2 Fighter and 2 Barbarian bring +4 Fort +4 ref +1 Will, so the character who took the two dips lost +4 Ref and +1 Will in exchange for a gain of +2 Fort.
It is incongruous that switching for 2 levels from one class with a good progression in a certain save to another with a good progression in the same save allows one to have a 5% higher bonus for that save than would have staying in the first class. Seems like an unintended motivator for multiclassing provided by the initial +2 for "good" saves. Without that +2 modifier, the difference in Fort saves between a 2 level Fighter plus 2 level Barbarian versus four level Ranger disappears.
Maybe the convention of starting "good" saves with +2 upon entry to the class as well as advancing at +1/2 levels is too generous.
What if level 1 of any class had +0 for everything (saves, Bab, Ac, damage), and the character won bonuses only upon leveling up?
I suppose we might rationalize the RAW assume a level 0 that we don't play, and martial characters get +1 Bab for making it to level 1. Perhaps the game should tax multiclassing and thereby even things out by requiring one level of level 0 play in the new class. (so the Barbarian 2/Fighter 2/Ranger 1, playing as Barbarian 2/Fighter 2/Ranger 1 has gone through at least two level 0 levels ( Barbarian 2/Fighter 0, and later Barbarian 2/Fighter 2/Ranger 0). In this system, if the player had initially chosen and stayed with Ranger, the single classed character would be in level 7, saves +5/+5/+2, Bab +7/+2 when the multiclassed one reached fighter 2/Barbarian 2/Ranger 1 with saves +6/+2/+0 and Bab +5, while RAW would have the single-classed character at Ranger level 5, saves +4/+4/+1, Bab +5.