The idea of a cylinder is not so bad anymore that i first thought
If you're asking for a cylinder with the same horizontal and vertical dimensions as currently rendered, you're increasing your boubble volume by 50%. It would equal an increase of 14% radius if it was to remain a sphere.
The devs give us little chioce to play with the rendering distances of the world / aircraft / ground objects. If they did, they open the same can of worms as it exists in FSX / P3D / etc when everyone wants to move the sliders to the right and they end up with a stutter fest. While with a proper flight sim, this might be acceptable as people can make the best of what they have, putting the bar that high to make a good combat game is probably not so helpful. The devs have to come up with 3 or so balanced packeges of settings that make the game run well on most of their clients rigs.
Assuming CPU/GPU overhead scales about proportionally to the size of the player bubble, you're asking for 50% more render time which comes at the expense of something. Currently, if we fly at 10'000 m altitude, we cannot level bomb, because we see only what is directly under us, leaving the bombsight "empty".
Then again, what was the common altitude that was used by the Luftwaffe to do so? Question is, dies the game allow you to reproduce the missuions that were flown back then? I guess it mostly does.
What I would think would be better if there were different classes of objects to be rendered at different radii from the player. Big ground objects fartehr, contrails farther, as soon as there are no contrails, you can let them enter player's vision at maybe less athe 6 km. But once detected they stay visible until you pan away your sight, losing sight of them as a compromise not to keep many planes in an ever expanding player bubble.
In general, I think we have a good compromise here. We get good FPS permitting even VR. Good enough to chase each other around.
A real perspective from an aircraft looks very different, here an example from Prepar3d v3.4. On an i7 at 4.4 GHz and a GF1080 i manage ~45 FPS to render this:
You can see, from 10'000 m over LAX I can see in topdays weather for about as far as Santa Barbara. Half a BoX map. 50 km render distance of ground objects.
Largely removing the athmosphere (clear skies) it looks like this:
I can see as far as Vandenberg AFB, 220 km away, almost a BoX map in each direction. 50 km draw radius for ground objects as well.
What is also painfully eveident, drawing the small combat playpen cancels out proper perspective on the globe, hidden in the haze. The higher you go, you should see the horizon getting lower under your nose. See here:
At 1'000 m the horzion is centered in your sights.
At 6'000 m, the horizon is already below your sights.
At 12'000 m, the horizon is below the hood.
Also note the curvature of the earth. Sunset and sunrise will appear as a shadow front across the globe.
The entire approach on how the world is rendered in BoX is a compromise to make "the world as we use it" pretty enough. But you discard a lot of aspects as they are not relevant to gameplay.
Personally, I think what is an issue is that ground objects need to be rendered farther out. Not only for level bombings sake, but also for improved dead reckoning.
The "more real world", as depicted above just doesn't allow headroom for including CPU overhead for DM and AI. At least not with the hardware and software tech that we have right now.
As for planes, most people spot planes IRL only once you're already colliding with them. If there are experienced pilots in here that can routinely spot aircraft over 6+ km, that's awesome, but highly unusual. Spoting an aircraft with your eyes is not thesame sport as tracing it. I doubt most people can spot routinely >5 km. . Spoting at distance requires you to rain your eyes to have their resting focus at infinite. That's not us desk jockeys.