You want every single cell phone call in the world to send out a signal over every single cell tower?
There's not a legitimate engineering reason that the network needs to maintain constant fine-grained location data for each registered device at this point. The scope of the registration can be far more widely cast.
This would even have upsides for the devices and users. As check-ins to the network in which the device must transmit to the network would be far reduced, battery life improvements can be had.
Yes, this increases the amount of "broadcast" traffic, but honestly, even for some of the busiest telco switches in New York or LA, those data streams don't even approach the throughput requirements of a single HD Youtube stream...
What is the passive bitrate of a tower->cell connection? LTE/GSM whatever.