I think you can safely assume that it's cost cutting, but it's probably a reflection of today's drivers who rarely look at their gauges anyway and wouldn't know what a temperature is trying to tell them. I too prefer a gauge as you see what's happening before it gets to the point of serious damage to the engine, but the red light if observed and acted upon should provide sufficient warning of trouble. Like you I also believe a tachometer is a not needed in most cars.

It’s not possible to say with any certainty when your clutch might we worn out, but you’re already doing well having clocked up 105,000 km. You can normally tell how far the clutch has worn by the height of the clutch pedal at take-up. If it’s close to the floor there’s plenty left in it, if it’s at the top of the pedal travel it’s probably getting close to worn out.

IT COULD be the plug leads, or the ignition coil, even a sensor. Have your mechanic check it again.