This incessant nagging about fps is the most tiresome thing in gaming since gamergate.

Yeah how dare consumers expect their products to be good

Good ≠ a single metric.

Sure, but a game is objectively better if it can run at a higher framerate.

Bloodborne is excellent, but it would be 100% better if it ran on solid 60 FPS.

Computers (including consoles) have limited resources, at some point you need to deal with tradeoffs, for example do you prioritize graphics quality or do you prioritize FPS? Do you want/need to have more resources available for the physics engine? That eats on the maximum possible FPS. Do you want to do real time procedural generation? Do you want to use the GPU to run some kind of AI? All this are design considerations and there's no one size fits all prioritization decision for all videogames. Clearly the people working on Starfield believe that for their intended game experience graphic fidelity is more important than FPS, and this is a perfectly valid design choice even if you don't agree with it.

It's a matter of optimization and Bethesda games have all had pretty poor optimization. They could get it running at a higher framerate but there's no need because people will buy it even if it runs 30fps.