Pax said:
... on a regular, reliable basis.
So when the Rogue can regularly (with flanking) deal out more damage per round than the fighter ... IMO there's something in need of fixing. 
Whoa.
All enemies in your campaigns can be flanked, have no applicable miss chances, aren't invisible, blinking, or immune to critical hits.
So no arcane casters, no displacement, no blur, no rogues, no barbarians, no undead, no oozes, no constructs, no fortification armor, no plants, no ranged attackers, no creatures with a high AC, no grappling, no swallow whole, no incorporeality, no attacks of opportunity, no improved grab, no counter tumble...
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Jeez. I'm of the exact opposite opinion. I think high level SA is mediocre. What caster is not going to buff with a Displacement after seeing the first SA? Or even before? Displacement or some other miss chance is a must for high-level play. (Entropic shield vs. Rogue archers.)
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Sure, in a low-magic world, SA is overpowered. Since all of your enemies are humanoid non-casters with few magic items, then SA works against everything. With the money limits in the DMG, however and a typical amount of casters, the DM is free to pull out the stops for NPCs and creatures. Potions are an NPC's best friend. Casters buff. Creatures Sunder. SA just requires that the DM not fall back on base MM creatures.
Sure, a Rogue will rock a Tarrasque...
...but a
L4 Sorcerer Tarrasque would rock any level Rogue.