So, for tea at least, and green tea in particular, water temperature is actually very important. This is often overlooked by people (at least in my experience in America). I've had many friends who claimed to hate Green Tea because it is bitter. But they changed their minds when I brewed them a cup and explained that it is important not to burn the leaves with hot water and then over-steep the tea---rather than boiling water you often want water considerably cooler, say 150-180 F, depending on the tea. You also don't want to steep for too long (often just a minute or two, again depends on the tea).