We've got enough tree's afaik, we've now got more tree's than we've had for a long time, because everyone's solution, is to plant more trees, but, people arent using wood as much as they used too..
Theres also the bit about tree's not being the best way to pull carbon out of the air, there's sea grasses and stuff like that, but from a PR POV you can see a tree easier than sea grass, so we plant tree's instead because looking like you are doing the right thing is usually more aesthetically pleasing than actually doing the right thing...