https://wccftech.com/microsofts-xbox-series-x-has-70-more-airflow-compared-to-xbox-one/

The Xbox Series X console definitely has a peculiar form factor compared to the usual gaming system. The closest match might be Nintendo's GameCube in that regard, although Microsoft's upcoming next-generation console is about twice the size.

Speaking to Eurogamer's Digital Foundry, Chris Kujawski (principal designer at Microsoft) revealed why the team went with this choice for the Xbox Series X.