…which is exactly what Risa demonstrates, in a configuration some of us determine fairly reasonable, given the engineering constraints, which guide the design parameters.
…but once again: The sweet spot is not something you “look at”; It is a location in space, where you (or to be specific: “the pupil of your eye”, is.
It also optimally expects you to look along the axis of the lens - perpendicularly through its centre.
…and, also again, there is nothing magic about the centre of the lens, that somehow makes everything clear, regardless of which direction from which you are peering through it.
Bringing the lenses closer together could indeed offer more stereo overlap, *IF there is more screen behind them (…and, with canted screens, it is not too far away in front).
I would certainly appreciate more overlap, and more clarity, but… (as it happens, btw; Given my low IPD, there is less room for more overlap, than for somebody with wider, since I’m closer to the inner edges, where the screens impose on one another’s space.)
A little story about different tradeoffs (numbers not properly recalled, and taken out of thin air, to spare myself the research :P):
So you had the HTC Vive and the Oculus Rift CV1.
Both these devices have a 1080x1200 pixel screen for each eye, but they look very different.
With the Vive, these 1080 pixels horizontally are spread over just under 100-ish degrees for each eye, and when you use the device, it gives you almost 100% stereo overlap.
With the CV1, Oculus balanced things slightly differently: By giving each eye only 80-ish degrees of field of view, their 1080 pixels didn’t need to stretch as far, which blessed their device with a 20% resolution (not in bitmap size, but in real world measurements: Pixels Per Degree) advantage over the Vive, at the cost of a more claustrophobic experience.
To ameliorate this situation, the Oculus engineers decided to skew the lens-to-screen alignment, and the camera frusta for the left and right eye game camera, so that the left eye could see 5-10-ish degrees farther to the left than the right eye, and vice versa.
This way they sacrificed some stereoscopic overlap for a greater overall FOV, both eyes taken together. This still left this resulting rectangular-ish field of view, remaining 70-ish degree stereo, and two times 10 mono added together, fitting entirely within the round stereoscopic portion of the Vive’s, but it was an improvement of sorts, allowing them to keep the higher resolution, and with the slightly offset lenses, it felt to most users as if the Rift had a significantly larger clear area part of the view, than the Vive, since at least one eye was in focus out to the side, even though the other was beginning to blur – this was strengthened by a simple matter of relativity: X degrees of 80, can be perceived as more than the exact same X of 100.
Oculus’ marketers also came up with the notion of presenting the FOV of the CV1 as the diagonal of that rectangular view, rather than the width.
…you may be picking up a parallel or two, about now.
I haven’t made any proper measurements, but I am pretty sure the binocular overlap of the 8k/5k is even worse than that of the CV1. For some reason this still doesn’t feel as extremely uncomfortable to me as that of the Rift’s. My speculation is that this is because whereas the per-eye views in the CV1 ends abruptly, as a vertical edge which is sharply in focus (whilst the other eye keeps going for 5-10 degrees), the (even earlier) corresponding edge in the 5k+ “fades” out of focus, so that the terminator isn’t as jarring – something of a silver lining to a severe weakness.