he did mention it in the video. i think that area would look cool and be a good hiding spot for camping CTs or those saving, but he also said that the changes he was making were primarily gameplay based, rather than aesthetic. The reason he expanded banana was (to the best of my knowledge) to make CT sniping less overpowered and to prevent it from being simply smoked off. The new area would have to be thin, and as such could be blocked off easily with one smoke or an incendiary grenade.

Disclaimer: this is coming from someone who is really bad at CS:GO, so don't take my word for everything.