Their idea (not a rule) is not to raise hood heights, but rather...
"The solution is to provide sufficient clearance (greater than 10 cm) between the bonnet and underlying structures for controlled deceleration of a pedestrian's head. However, considerations of aerodynamic design and styling can make it extremely difficult to alter a vehicle's front end geometry to provide more under-bonnet space. Active safety systems, such as pyrotechnic devices that rapidly raise the bonnet in a crash (fig (fig4),4), can provide the necessary deceleration space during an impact while maintaining traditional bonnet geometry during normal operation of the vehicle."
I would think the iX's engine components would be configured similar to the Tesla's and allow a much lower hood. I hate to think how much range the iX is giving up pushing that barn door through the air.
I do believe that the high hood, massive front end, and big grill with no radiator to cool (in the iX) is all about what BMW (and others) view as styling that will sell vehicles. It must work, or they would try something else.