Loving wood is fine, but you need to demonstrate "progression" and a feeling of achievement for players by varying up the environment. Generally speaking, in regards to the facade system in TF2, players will progress from the out skirts of a base to the inner area which is more built up and industrial. IE wooden shacks and cliffs>full on wooden structures>metal, contrete and brick structures.
It could be argued that forgoing the progressive theme is counter-intuitive to TF2 lore. But there's a large margin for error so even including at least a few metal structures will be a massive improvement. So it's not just a matter of "lots of wood is ugly" it's also relavent to the narrative of any map, especially A/D.