So one of the more interesting pieces about the Constellation is that it has substantially more internal volume than similar vintage ships like the Constitution or Miranda. At 640,000 m^3 it's actually almost on par with the Excelsior in overall volume. When nacelle volume is excluded the similarities in overall volume increase. (Excelsior has a slightly larger nacelle volume overall)
Given that there was at least one Constellation class ship stated on-screen to have been commissioned in the 2280s, this raises the question of whether the Constellation was considered something of a "back-up" plan in case the Great Experiment wound up being a flop. The four-nacelle arrangement, the extra volume and the fact that a fair number were still frontline explorers into the 2330s — 2350s suggests they were overengineered to a similar degree as the Excelsior.