The difference is rather slight, not enough to create a "warship vs. peaceship" contrast here. There could be completely obscure technological or political reasons for not installing aft torpedoes on the Enterprise
, just like various obscure concerns dictated whether a WWII battleship would be built with 2+2+2+2 or 3+3+3 main guns, neither configuration being necessarily better or worse than the other.
Perhaps the Enterprise
is a newer and more agile design and for that reason doesn't need rear torpedo tubes to cover her ass?
As for the torpedo tubes of the Constellation
class, we see little evidence for their presence or absence in "The Battle", but OTOH dialogue insists that they are there. Quite possibly they could be found in their "proper" places at the junctions of the engine pylons, then, if we just could see there. When we do see a close-up of that part of the ship class in "Peak Performance", there is no dialogue to insist that the ship would be armed with torpedoes. Perhaps Starfleet faired over the torpedo tubes when it retired USS Hathaway