Nice article!
ToR designs have a lot of advantages. Depending on the type of deployment the best place to put them is in the middle of the rack.
This further reduces the total cable length and improves the airflow.
IMHO The space utilized by the switch, is gained by not having to have a 48 port patch panel in the rack, and then another set of of panels at the End of Row. This is especially true in situations where you are deploying high density racks with 40 – 80 servers per rack. I know that a rack is typically 42 U, but Rackable used to make half length 1 U servers, that could be place back to back. When it comes to wasted space I have seen a half rack on both sides of a core server used up by patch panels. This is an entire rack not being used. If you figure that you will have the same amount of panels in the racks, that is two cabinets.
There is also a small savings in core switch space used and money since they are much more expensive per RJ-45 port. Although the cost of fiber.
A big advantage to reducing cabling is improved airflow. This is the big problem in high density deployments. Another advantage is ease of troubleshooting, If you have 300 patch cables going into a core server, it can become a mess. You are also cutting the number of connections in half since you are not using two patch panels with two patch cables.
Having fiber reduces long hauls of copper, which sometimes runs close to high voltage.
When the cabinets have wheels, the entire rack can be configured and tested by the vendor, reducing deployment costs. Wheels also provide the ability to move cabinets to better manage heat issues. Because of this flexibility you can pack more racks in.
It also gives better negotiating leverage with Data Center. This is what Google would do, before they were building their own data centers.