Mmm. It's the same thing the Axanar team did on their ships: the smaller size fits the rest of Trek better. Not that Starfleet couldn't have bigger ships than Kirk's TOS one, at any timepoint - but it was just too attractive an opportunity to pass when the
Kelvin sported the registry of a
Saladin class ship that looked more or less exactly the part and could well take a dorsal pod and an "O prefix", TAS style.
There are surprisingly few scale-establishing things about the
Kelvin in the end; if anything, the bridge suggests the Guide/Axanar size if taken to occupy the center of the superstructure rather than the forward edge, and there are docking ports that would be immense on the larger interpretation of the ship. Even the ships seen later on in the movie could be of the smaller scale, as we never get a good comparison with the hero ship, one devoid of perspective issues. (The hero ship meets with two separate wrecks of giant saucers, both labeled
Mayflower, in the debris field above Vulcan, but none of the cadet-crewed ships was named
Mayflower anyway, so this double-saucered giant could be some sort of a
Deneb caliber battleship that responded a bit before he cadets did!)
Not only does the
Kelvin look like a
Saladin, but the big twin-secondary-huller is a dead ringer for the
Proxima battleship of RPG/computer game fame, again at the smaller scale. And it sort of follows then that the nacelles-down ship would then be related to the
Burke of the RPGs.
Now, this is still intended to be how the ships "really" look in the "altered timeline", as the ships don't suddenly change size just because Nero time-travels. The one thing casting a bit of doubt on that is in ST:ID where we get a scale-establishing shot of the big space station above Earth, that is, a shot with the hero ship docked. But I'm turning a blind eye on that.
The new hero ship of course
is in the size range of the E-D, and has every right to be, as the "regular" universe introduces large command ships (say, the
Lexington) around that time as well. And the
Vengeance then is
almost as big as the Duaneverse
Deneb...
Timo Saloniemi