And don't forget that MGR never intended for our cars to be on the road 20 years later. That wouldn't be good for business!
The Jatco autos really do benefit from a drain and fill occasionally. I would do a partial change on my Freelander's auto box every year and it made a big difference in driveability.
As for MTF94 Ravenol also makes oil in that grade. Theirs isn't cheap though!