My intuition is that the remote and unlikely chance of those designs being needed would make the calculable benefits so small that they would not be worth the trade-offs, both in the immediate construction costs, but also the costs of everyone actually using a building designed with too-long walkways, non-optimized layouts, etc. over the entire projected lifetime of the building.

Let us all walk around concrete obstacles for fear of an unlikely attack?

Schools turn into parkour training gyms. Might help against youth obesity (probably saving more lifes than the shooter protection aspect...), but excludes students with disabilities.

If safety is really what people value, sure. But I am not sure I want to have an architectural space that reminds me of living in fear all the time.

Besides, architects have been studying this stuff before there were video games. Christopher Alexander made a study of traditional and modern architecture to develop “living architecture”. He defined architecture as spaces that shaped human interaction and emotions. Fear, safety, and security are only one part of the spectrum of human emotional states and concerns. I think I would rather send my child to a school whose spaces are designed towards learning and exploration.

These principles are presented in the context of a game, their goal is to make the gameplay more fun. Applying these to real life seems a long shot.

A discussion about real life safety, while important, IMO feels a bit offtopic.

Or you could nerf the shooters.