[Archer6621]

That's a good question, I wonder about this too.

The games that have the entire environment covered by one screen all share this same frustration of getting surprised at the borders.

But another thing that also used to be popular was the infinitely wrapping environment (sometimes on one axis, other times on both) that would span across a larger area than the screen, which is still really cool. Some old windows games such as Vangers, Operation: Inner Space and Astrorock 2000 used to do this.

I guess both cases applied better to 2D games, specifically more arcade-y space stuff, so probably it went out of style when arcade went out of style, and when 3D game environments (specifically first/third person) became more prominent.

Another thing that I found is that implementing this wrapping yourself while using a commercial game engine, without actually fighting the engine, is usually quite tricky, as most aren't really built to deal with this sort of stuff. That might be another side-reason for not being as popular anymore.

[masswerk]

I think, a bigger, virtual area may be even more difficult to handle. In Spacewar, it's an exact square and all of it is shown on-screen, including immediate transitions to the other side (which is replicated here), while in Computer Space, it's also a square area, but the visible screen area is just the standard NTSC 4:3, including a vertical off-screen area and an invisible bit of horizontal blanking at the side(s), where the saucers may hide, while still attacking you. Personally, I find the latter more difficult or even irritating.

[shadowofneptune]

I quite like how Star Control II does it. The camerawork is fairly polished, but the main anti-frustration feature compared to this is that there's a health bar.