Not sure why they kept it around for so many model changes but they have.
Probably because it was cheaper than re-engineering, re-certifying, and re-programming the assembly line.
You think I'm kidding ?
One outfit I worked for bought some passenger seats for the upper deck of a freighter, they had the little video screens fitted in the backs, but of course no IFE equipment was on board to use them, so they just took them out.
The UK certification authority refused to certify the seat installations without new engineering drawings, manuals, etc. to show the empty space in the back of the seat.
This meant going back to Boeing for the engineering drawings to be created, and the FAA for certification of same -'cos it was originally a freighter from a previous US carrier - before changing the Reg'n. for the UK Register, at great cost, as you can imagine.
It was cheaper to put the screens back in and just ignore them !
Bureacracy Rules - O.K. ?