It occurred to me to wonder whether part of the problem had to do with pressure, either from the market or from regulation, for energy efficiency. The external dimensions of a built-in dishwasher are fixed. One way of making it more energy efficient is by putting on more insulation to make it easier to keep things hot while they are being washed—which also makes it quieter. More insulation is likely to mean thicker insulation, which means less space for dishes. Along similar lines, the new dishwasher, unlike the old, doesn't have the option of hot air drying—dishes are dried (or not dried) only by the residual heat from the washing. That saves energy, but makes the dishwasher a good deal less useful.
Does anyone reading this know enough about dishwasher engineering to say whether new dishwashers are, typically, worse than old for these reasons? Whether, if so, the problem is energy efficiency standards set by regulation, or merely the advantage of being able to advertise energy efficiency and low noise?