Dear twinmo, I beg you add new type of trees in the future updates. Having a year of experience using this program I can say that the only disadvantages is the lack of trees in the library. For ar...

I agree, and this render is a good example of how thin trunked, tall crown trees reveal the subject and yet don't look unhealthy and spindly.

As a workaround, I've sometimes played with tree Age and Scale.

For instance, London Plane at 30% Age and 100% Scale is too chunky. The 5% Age version has a good thin trunk, but the crown is too low. Increasing the Scale makes the same young tree shape taller. Unfortunately, the X and Y axes are locked to Z, so you can't play with width - but at least foliage is out of the way and you can see buildings from eye level.