Wow! This can be a tough crowd!
When posting this question, who would have predicted that this topic would generate some of the responses that it did, including such favorites as, “have some kids or something!”
Well, getting back to the question of gauges versus warning lights my view is that this is the difference between “monitoring” the vital signs of the car as you drive versus “riding” in the car. My view is that manufacturers have gone to warning lights as a cost savings measure and not for improved monitoring. If warning lights were the answer, then hospitals would take your blood pressure or body temperature and the only indicator would be a “green” light for “good” and a “red” light if there was problem. But they don’t, and the reason is the same as why I posed this question in first place. Gauges allow monitoring not only the fact that things are currently, “OK” but also identify “trends” which allow the user to identify potential problems and determine if any action should be taken before damage or injury occurs. Sometimes seeing a "red" light is too late!
Another reason why manufacturers have gone to “warning lights” is that they don’t want to deal with customer complaints and the resultant warranty costs that occur when the customer brings their car in because they have either been told by the service department or in the owner’s manual that their oil pressure or water temperature should be “X” and their gauge shows a discrepancy and they are insisting that the vehicle be “fixed”. Vehicle manufacturers have learned that it is easier (read cheaper) to provide their customers with the sense of security that an "unlit" instrument panel light provides instead of the real time info that a gauge provides.
Remember, there is a reason why “warning lights” are also called “idiot lights” and the answer is not just to, “have some kids or something”.