What makes a staircase look dated
Walk into a lot of Dallas and Carrollton houses and the stairs tell on the era: carpet over the treads, turned oak spindles, a round builder-grade newel at the bottom. Nothing is broken. The stair just belongs to a different decade than the kitchen next to it, and it is the first thing a guest sees from the front door.
Because the staircase is such a big piece of the room, changing its lines changes the whole house. Marlon and his crew look at a stair that way, as one composition where the treads, newels, rail and infill all read together instead of as parts to swap one at a time, so the finished run looks like it was drawn that way from the start.