Everything fails eventually. Thermostatic switches fail. Relays fail. Temperature senders fail. Fan belts, fan clutches, heck even water pump shafts and bearings fail. I have seen plenty of mechanical fan failures, they're not immune. And when they do fail, they take the radiator with them a lot more frequently than electric fans do. Modern electric fans are much more reliable than they used to be, and most of the problems people have with them are poor installations and improper triggering/controls.
And the Dakota Digital controller is not "technology for the sake of technology". You can not do what it does with just a thermostatic switch. One of the biggest advantages to running an electric fan is improving efficiency- running the fan only when needed reduces parasitic power loss, and keeping the engine in its ideal temperature range improves power. A digital controller does a much better job than a simple thermostatic switch.
