Tea is personal — there is no objectively correct way to prepare it. Rather, the goal is to find the magic combination of water temperature, steeping time, and leaf-to-water ratio that produces the infusion that tastes best to you.
When we give a recommended water temperature, that is what the grower-artisan believes will bring out the flavor, aroma, and color that he or she has striven for.
In other words, over the years, when a grower fine-tunes the many variables of tea crafting — harvest time, steaming time, and the intricacies of shaping and drying, for instance — he has done so according to how the tea tastes when brewed with water at that temperature.
But most growers also understand that tea is a personal journey. No two artisans will brew the same tea in exactly the same way, and tea aficionados endlessly debate such matters, too. But can anyone tell you that you are brewing a tea incorrectly, if you like it better that way than when brewed according to that person's rules? Feel free to experiment!
However, to have a baseline for that experimentation, I recommend first trying the tea as brewed according to the artisan's guidelines.
Then, let the journey begin. The treasure at the end will be worth it.