If you drink green tea and pour in after boiling, you are not getting the best benefit and taste from the tea b/c the hot water is burning it and it will taste bitter. When I got my variable temp kettle, I learned a new appreciation for Green Tea.
Maybe this is why I don't like green tea and herbal teas. They all taste like grass to me. Some of them smell wonderful but taste like I just steeped a bunch of dried glass clippings in my mug.
I drink mostly Earl Grey and orange pekoe and always put the water in while it is still boiling a little bit. I'm so fussy that I carry a little 4 cup kettle with me whenever I travel to have in the hotel room. Hot water from the coffee pot just isn't hot enough, not to mention tasting vaguely of coffee. Blech! I was on a course and the caterers delivered hot water in a pot that had previously held coffee. It was the most disgusting tea I've ever tasted. Ever since then, my kettle goes with me everywhere I think I might need it. And I take my tea with me, too.
I had the same problem. I was introduced to Steeped Tea when I was home in Canada this past Sept - they were on Dragon's Den. Have you heard of them? I had not drank tea in a very long time, since university when I switched to coffee to function. Never went back to tea until I was re-intro'd this past Fall.
When I tried the Steeped Green tea here at home (it is now in the US), I did not like green or white tea.. they all had no flavour or tasted bitter. It wasn't until I got the variable temp kettle that I really learned that the temp of the water makes ALL the difference.
I made a cup of the Coconut Calypso this morning for the first time after getting my new kettle. I tried it when I first ordered it and didn't like it.. it was bitter and had no flavour. WHAT A difference! I can taste the coconut and the tea doesn't taste like you described either.
If you are a big tea drinker, I suggest you check out Steeped. It is competitive, if not better than David's and not as expensive. They were on Dragon's Den a couple years ago and got funding from Jim Treveling and Rick Chilton of Wealthy Barber.