That triple viewscreen...
Lines up with what do look like bridge windows.
So Starfleet was toying around with window viewscreen tech as far back as 2233 at least.
I don't see it as a retcon. One thing that has been a common element in viewscreens is that, other than the holographic one on the Enterprise-E
in First Contact, they've ALWAYS been on and most of the time showing what's ahead of a ship.
Frankly if the Enterprise
in Wrath of Khan had a window style viewscreen it might have made spotting the Reliant easier because while the Mutara Nebula interferes with sensors, sometimes it would just be easier to look out the window with a Mk. 1 Eyeball.
Some might see the window style as a structural weakness, but you have to consider that maybe its some kind of transparent metal like the normal viewports on the ship.
I didn't notice that on the outside view in the clip, my eyes aren't quite what they used to be I guess (and I did not do a frame-by-frame). There are some problems with those being windows (though after seeing them it is obvious that they intended them to be), such as from the inside those were opaque black when the screens flickered out during hits, though I suppose they might have blast shutters or something that they close before the battle or something.
Also, the 3D model builder and the set designer should have coordinated a lot better (if they did at all). I do not have my old analysis tools on this machine (it is Windows instead of Linux) but just by eye it looks like the angles and sizes are significantly off (they probably figured on action movie fans who are just in it for the "cool" looks and stunts instead of "trekkies" who measure and test everything). Really, for something with windows like that it is best to have the modeler continue the model inside for important rooms that connect though the hull like that so the set designers know exactly what they have to work with, even if that means having the construction crew build a full size simple cardboard mockup of the empty room that the set designer can walk around in (for some of the less tech oriented set designers).
And the angles and sizes of the window openings between the outside and inside views is not the only angle problem. The "JJ windows" are probably meant to be the transparent aluminum that was mentioned in The Voyage Home
which according to dialog has about the same refractive index as Plexiglas, which is a problem since the outer window face is more sloped than the inner one is which makes it a prism, so the view out the window would be skewed instead of straight ahead. At the very least it would make for a lot of really weird reflections and maybe even auras from the refraction.
And yes, it would be a significant weak point to attack (though to be fair the Kelvin (and DSC) fire control is so lousy they often miss other ships when they are practically touching so they may not be able to hit something that small on purpose) since aluminum has a very
low melting point compared to tritanium or duranium, it would be like using paraffin with the kind of temperature numbers they sling around in dialog in various episodes. It is even worse than that though since even a laser or nuclear flash or whatever that is too weak to damage the hull would pass right through the window like the frame was empty even before
melting anything. The crew would be like ants under a magnifying glass in the sun.
Then of course there is the fact that besides the pretty starscapes (which realistically might not even be visible with the bridge lights on) there is nothing actually useful to see anyway at the ranges they supposedly fight at. That is especially true if you take TOS into account, even something the size of an aircraft carrier would be difficult to spot at the average TOS combat range of 40,000 kilometers and that is assuming they are even fighting at sublight speeds (statistically, most TOS battles happened FTL, between warp 2 and warp 4 according to the dialog in the battle scenes). They might as well hang paintings on the bridge for all the good an optical window would do them.