Umm, isn't it rather vice versa? In TOS, it is difficult to make a torpedo find its target, be it a speeding Orion ship or a tiny Nomad, but when it does, the target is history. In TNG (and supposedly in TOS, had the occasion arisen), single torps can demolish unshielded targets, but one may need to literally expend a shipful to make a dent in the shields of an opponent.
In every era, skippers seem to prefer engaging with phasers, and torps basically see action when there's a need to discourage pursuit, or engage an unshielded target, or to fire at least something when your own ship is damaged and power levels are down.
But there's plenty of ambiguity in every era. The one thing specific to the 24th century is the risk posed by the torpedoes to the firing ship herself at close ranges; Kirk didn't seem too worried about this when playing 'possum to the Orions or firing at Klingons en passant.
Timo Saloniemi