As others have hinted above, there are two sets of rules for hot water from storage that conflict.
One is that the water should be stored above 60° and should reach the tap at 50°C within 30 seconds. The other is that water should reach a bath at x degrees, and I'm sure I read somewhere that there are recommendations for a washbasin also.
The issue here is that the regulations for maximum temperatures apply to new bathrooms, not to existing ones. Your plumber has fitted a new cylinder and presumably set the storage temperature to around 60°C, which is correct. He has also not fitted a blending valve on the cylinder outlet, and was right not to do so as the water running through the pipes needs to be hot enough to keep them hygienic.
If you want to upgrade your bathroom to current standards regarding maximum temperatures, the right way to do it would be to have thermostatic mixing valves fitted directly under the taps to temper the water while allowing the hot water in the pipes to be hot enough to prevent biofilms forming. Personally, my feeling is it's just something else to go wrong, but if you want the water blended down, I do understand.