Like many photographers I guess I have usually been guilty of leaving my cameras in matrix, evaluative or whatever other clever metering options the camera makers give us in the interests of getting a good and safe overall exposure.
This is often a sensible option for many general types of photography and if shooting fast where you don't wish to miss moments. The idea is that the chosen exposure will try to capture highlights but also preserve shadow detail to give a safe overall exposure without clipping tones at either end of the histogram. Of course, I understand metering and will use spot metering for example, if I am trying to get skin tones correct against a bright background, but there is much more opportunity that beckons with spot metering.
As photographers, maybe we should think more about what we want to show in a particular image and sometimes stray away from the safe ground of these clever metering modes. I have recently thought a lot more about this while shooting weddings, street photos and daily family shots with my little boy. Some photographers manage to get richer and darker tones, more tones across faces and dramatic use of shadows that would otherwise look insignificant if a "safer" exposure was used. The way that photographers I admire like Jonas Rask and Kevin Mullins use dramatic lighting contrast to make their images stand out is very clear. It can really enhance images of people or where you want to highlight a subject and simplify a composition by making other elements fall into darkness or near darkness. I am not suggesting it should always be used or even be the main method one uses, just that it is worth considering.
A technical point is that with the Fuji X cameras you can link spot metering to the selected focus point rather than just the central area of the frame, which makes spot metering very useful in off-centre compositions, which is what most are after all.
Here, I wanted to really highlight differences in shadow and light and expose more for the highlight tones, to deepen shadows and make people stand out on the "edge" of the light. Apart from the main subject, exposure was set so that people in the background would appear from deep shadow too. I used spot metering on the skin tones of passers by and locked exposure with the AE lock button. I zone focused to allow instant shooting and avoid delays in waiting for AF to work.
Here the background was busy and I wanted a greater range of skin tones so I used spot metering on Theo's face. The detail there is in the shadows still gives context but detracts less from the obvious subject and the image has the lower key look I was seeking.
Similar here, same place, same day. I just wanted a lower key look with bias on the skin tones.