c'mon, let's not pretend people actually stop driving when they lose their license - In 99% of the US, "not driving" amounts to a sentence of death-by-life-on-welfare
Why not use a mass transit service like subway or tram?
I'm talking about both. Level design definitely suffered from efficiency loss after transition to 3d. Gameplay design is a different issue. It didn't get much overall progress since 1990s and is treated as afterthought compared to graphics currently.
Employing a 3d engine imposes some limitations on design stemming from assumptions made by engine's author. They tend to be oriented for first person shooter games. And most game programmers don't have resources or skill to roll out own engine. Besides, requirements for artwork ARE a limitation too. They definitely limit the amount of gameplay elements allowed. Say, if you decided to avoid models and use 2d sprites instead you could save some work for artists. Which could lead to more creatures and objects and larger, richer locations. And GPU work itself isn't free either. It still requires assets such as textures and amount of those is limited by GPU memory. Reducing detail level of models and textures would lead to ability to have more different objects on screen at the same time.
All in all, AAA game companies given up on doing anything else than flashier graphics and I given up on AAA companies in response.
What does arbitrary geometry have to do with level complexity? My Nintendo 64 featured games with arbitrary geometry, and games with complex level geometry usually feature invisible, lower-resolution collision boxes; from a design perspective, those "are" the level.
Having more regular geometry allows the program generate more geometry itself and level designer to specify less.
Wrong. There's absolutely no reason that the developers couldn't tack on a graphics-based display of the content in the game world, with nearly arbitrary-detail tiles, and there's no way that doing so would limit the underlying game logic. "More triangles per frame" is primarily a function of GPU power, and DF's world runs exclusively on the CPU. The world's CPU-heavy; the graphics are CPU-light and GPU-heavy.
No reason except the requirement to maintain a reasonable framerate. There exist some graphics frontends to DF but they definitely don't use photorealistic graphics. And probably they wouldn't be able to get enough art assets for more detailed graphics anyway. Another option would be to move some processing to GPGPU because DF manages to kill framerates in some cases even if you use ascii graphics only.
A list is only as strong as its weakest link. -- Don Knuth