Back to the Franklin's armament being substandard for a ship of the Romulan War era compared to NX-01... two points:
1) Earth isn't the UFP at that point, they don't have limitless resources so perhaps the rollout of more powerful weapons like photonic torpedoes wasn't fleet-wide?
2) Perhaps Franklin DID have both spatial and photonic torps like NX-01, but the photonics are more prone to degradation of the warhead (particularly if there's an antimatter component) and thus weren't usable when Kirk took her into battle?
1) Earth isn't the UFP at that point, they don't have limitless resources so perhaps the rollout of more powerful weapons like photonic torpedoes wasn't fleet-wide?
2) Perhaps Franklin DID have both spatial and photonic torps like NX-01, but the photonics are more prone to degradation of the warhead (particularly if there's an antimatter component) and thus weren't usable when Kirk took her into battle?