A specific example of where it's useful to know the underlying mechanics: for very wide angle lenses, you will typically get brightness falloff at the edges due

A specific example of where it's useful to know the underlying mechanics: for very wide angle lenses, you will typically get brightness falloff at the edges due to a phenomenon called the cos^4 phenomenon (https://nvlpubs.nist.gov/nistpubs/jres/39/jresv39n3p213_A1b.pdf https://nvlpubs.nist.gov/nistpubs/jres/39/jresv39n3p213_A1b....). This is often elided by camera systems, that apply a gain to peripheral pixels to correct for this phenomenon. If you understand imaging, you will expect that, and understand why, for example, your wide angle lens displays a lower signal-to-noise ratio for a given illumination value than you might otherwise expect at the edges of the image. This is a really specific example, but there are dozens. Imaging is its own deep, technical field that is abstracted, and occasionally obscured, by the pinhole model.