Trying to fit the Oberth
in the continuum of starships is in some ways fundamentally counterproductive. Forcing her into the role of a "missing link" means narrowing down Starfleet's selection of hardware to just starships, even when TPTB appear to be doing everything in their power to have the Oberth
be something else altogether.
Whether she really is a scout class vessel as of the 2280s is uncertain; Kirk isn't quite convinced that Chekov's observation of a "scout class vessel" should be explained by it being the Grissom
, but rather just says, with doubt in his voice, that it "could be" that ship. Essentially, he seems to be saying (and hoping) that Chekov could have mistaken
for a scout class vessel.
Weak shields shouldn't be considered an artifact of the ship being old. Rather, it should appear natural that some ship types
have weaker shields than others. The Grissom
might even be such a "civilian" type of vessel that she isn't equipped with shields at all! (However, virtually all civilian ships ever witnessed have had some sort of shielding, even if it's useless in combat.)
The direct hit at the bottom being fatal is nicely consistent with TNG "Hero Worship" where the ship is depicted with a warp core -looking feature right down there, and dialogue even associates this feature with "core" (although the writer probably intended computer core there, yet thankfully did not make the intent explicit). A safety measure from ye olden days when warp cores were unreliable? A utilitarian engineering solution typical of smaller vessels (The "Hero Worship" ship is depicted with decks consistent with the 120 m length...)? A means of placing the "noisy" device far away from sensors?