It would be excellent if you can level them from level one. I have a few talents that I like on the heroes that I have, but they are at low levels.
Indeed it would be great if we were able to raise lvl of every talent, even from lvl 1, but unfortunately i also think it will not happen. Cause ppl would not look for lvl 5 talent to lvl it up that much, but for any lvl of needed talent, which is much easier to find. Although it would help us, it wouldn't necessary be good for IGG. Simple economics, so as much as i would like to see it... i doubt we will actually see this in game.