Looking at this TranzX system, it's simply a "de-skilling" tool....from a dealer's point of view such systems are a great money saving advantage: they don't have to hire electronic engineers to repair bikes, they simply have to employ and train up someone to use the software and the plug and play system to swap out entire bike subsystems, which report the required error codes...
It allows "proper" traditional "grease-monkey" bike mechanics who may be devoid of any electrical skills the ability to sell, service and repair a growth segment of their market with some confidence which they might otherwise shun. One of my local bike dealers is exactly that, a seasoned veteran repairing bikes since the 1950's. He can true a wheel in his sleep, but electrics are a complete anathema to him.
What I particularly like is:
1) It points you in the direction of where to look for the fault. It's not always a case of a wholesale component change.
2) You can of course update manufacturer firmware - or revert back to a previous version (as many Bosch owners have sometimes had a desire to do).
3) The "cloud" tells you when/where the bike was made, the bike serial nos (individual parts included - motor, display etc), firmware version and it's update history. It records a log of all faults and component changes to your specific bike over time. You can't give a prospective second buyer the "It's been thoroughly reliable, I've hardly used it" yarn to garner a better price because the full story is there, fixed for eternity in the cloud.
CANbus systems aren't everyone's cup of tea, but for some (both dealers and consumers) I can see they can be a good solution.