It is all a compromise. 37 PPD is well under the standard for normal "good" eyesight (aka. "retina" in Apple marketing), which is 60 (aka. 1 arcminute).

Doing more with a narrower field of view is easy, it is even cheaper. Doing more with the same or better field of view means you need more pixels and more computing power to drive them, so more expensive, heavier hardware that gets hotter and with less battery life.

People at Meta consitered 37 PPD to be a good compromise, and I kind of agree.