Why luxury appliances are better?
Premium appliances come with a much better design to finish of the fabulous look of the already well built kitchen counter tops and cabinets.
Designed for high performance, luxury appliances work much better. A top level cooktop puts more heat to work cooking dinner. A premium refrigerator might have multiple compressors that keep food fresh longer. Using the mineral zeolite, a superior dishwasher can dry dishes perfectly.
In general high end appliances are built to last for 20+. Economy brands will not approach that level of longevity. Factoring in maintenance and replacement costs, along with the inconvenience of replacing a cheaper model, the extra cost for a luxury appliance is mitigated.