After all, if the battle hull was intentionally designed to go into combat without the saucer, and if the saucer was intentionally designed to be left out of any combat situations, why in the world would the ship accidentally end up being more combat-capable with the saucer attached?
Not impossible at all. Just think of those combat aircraft that were designed with swing wings for adequate performance in two realms, but ended up being locked in one mode or the other, not just because of something having to do with the wings, but because they had to be built to a certain minimum size in order to accommodate the clumsy VG tech and thus became useless in that half of their role that called for small and nimble.
To build the sep/reattach functionality into the
Galaxy, the designers may have been forced to build a larger and more powerful ship than they at first wanted to. They'd end up with such a mean battlewagon that the separation thing would become completely redundant and even counterproductive in combat - and while agonizing over the details, they'd also decide to build a parallel starship class that omitted the sep/reattach function but otherwise was the same superb battlewagon.
The separation function may have been a complete operational failure to begin with, but technologically still good enough that half a dozen ships could demonstrate the concept (while dozens upon dozens of otherwise nearly identical
Nebulas would omit it).
Although, to be sure, perhaps the
Nebula class was also intended to separate and reattach? Its saucer section could omit the big impulse engines in order to take the idea of propulsively helpless saucer to its logical conclusion - while its battle section would be quite as badass as the
Galaxy one, or even more so, thanks to having the big dorsal module attached.
Timo Saloniemi