We build steel kitchens. So we'll start with what brick does better, and finish with where we lose. If you choose brick after reading this, then brick is what you needed.
If you want a single masonry volume that matches the house, you have a good bricklayer, and you plan to change nothing for twenty years — build in brick. If what matters is appliances that fit exactly, a module you can replace, how the structure behaves in an earthquake and a written warranty on the object itself — buy steel. And there is a third answer, the one we build most often: a masonry volume outside, a steel working run inside it.
None of this is an argument against masonry as such. It is what happens to outdoor masonry in a climate with a full freeze cycle, in a seismic city — and it is what most often has to be repaired.
Factory precision instead of fitting on site. The body is cut and welded to the drawing, and the aperture for an appliance is made to its real dimensions rather than to roughly that. And you choose the appliances: cooktops, ovens, sinks, taps, dishwashers, fridges — your brands, our apertures.
About the seams, straight away. You'll hear that modular kitchens leak at the joints. That's true of kit systems bolted together from ready-made boxes on site. We weld the body rather than assemble it: the seam is welded closed, the edges are flanged, and water runs off the outside instead of into the join. In stainless and in powder-coated steel that's a normal detail, not a weak point.
In an earthquake this is a frame, not masonry. A steel body anchored to the slab behaves as a frame: it can deform, but it doesn't come apart into separate stones.

Brick — but with a reinforced footing below frost depth and with the seismics actually calculated. Save on the base and you lose the kitchen.
Steel. Apertures cut to your appliances, a module swapped instead of masonry demolished, and ventilation that genuinely pulls.
Steel. The body isn't timber and is built for high temperatures, and the ventilation is commercial grade.
Most often the right answer is both. A masonry volume outside so the yard reads as one piece, and a steel working run inside it. We fabricate to drawing, so building into someone else's masonry is a normal job for us — several of our projects are exactly that.