I don't think that's an unreasonable question. Your answer suggests that we already have the most optimal solution, which by analogy cows would be too. I assume you know cows aren't.

But like with cows, it is not inconceivable that "regular" trees are not the most effective way of making wood. They need to stay alive which means they "waste" energy doing so. While I personally don't think we can outdo trees with regular chemical compounds, I think we can at least genetically modify some already-optimized tree family in a way that require less water, sun, etc.