It’s only useful on the 2016 & 2017 models. It allows you to access the soldered SSD storage when the logic board has failed. I guess it depends on what you see coming in and willing to work on. 95% of the time you won’t need it.
The newer 2018 uses the USB-C port in some manor which hasn’t been disclosed by Apple. This is due to the T2 design.
This is only important when you have valuable data on the customers system and they failed to backup.
Apple did this as the fear of people loosing their data was a concern for a Pro level system.
The heavy Pro’s either became more careful or just waited on the sidelines waiting for the REAL Pro’s MacBook Pro’s return!
With serviceable RAM & Storage (internal secondary), USB-A & Ethernet Ports! And hopefully a USB-C MagSafe interface. Finally a new (older scissor design) keyboards!
Rumors are percolating it finally will see the light! Hopefully with the Mac Pro’s intro at the 2019 WWDC! Hopefully this time Apple gets it right with proper cooling and maybe see both a 15” & 17” model.
It’s only a few weeks more cross your fingers! The PRO’s MacBook Pro returns! I’m personally in need of a new system I’ve been waiting way too long! For a system that meets my needs.