The standard answer to this is no, hot water is supposed to be hot.
Lukewarm water is an amazing breeding ground for all sorts of unpleasant microbes such as legionnaires disease. Legionnaires disease doesn’t survive above 60ºC so keeping the hot water temperature above this ensures the water is safe.
The second reason to keep your hot water hot is the storage cylinder is relatively small compared to the amount of water you need. The volume of the hot water storage cylinder is probably just enough to fill a bath. But if you use half the water from the tank and dilute it with cold from the main you could get two baths from the same small tank. This would save time heating the water again before use.
Mixing valves can be added to hot water systems to reduce the temperature of the water at the taps. This allows the water to be kept at a high temperature (above 60ºC) in the tank but still delivered to the taps without the risk of scalding.
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