no need to reprogram, just mass modify the tool length offsets or, set the Z axis in the tool coordenate system or use fixture offsets, all are easy 2min jobs.
and it doesn't have to take hours to reprogram, beleive me. there are more ways to compesate or translate in the software than on the machine.
comanders and suppers often expect us to work miracles in the machine shop to get a broke jet flying and keep up the mission capable rates and make themselves look better for promotion. riverbluff will tell ya, he was a crew cheif, they have it pretty bad at times. i've written programs from scratch with 3d and/or 4th axis geometry and had a part ready to turn over to structures for installation in the same working day. my point is programing and modifying programs isn't a long process in todays world of cad/cam software if the programmer is skilled and farmilliar with the software.
on the other hand they'd need to make thicker body blanks, and the entire stock of blanks the have now could only be used for non-recessed cover bodies, unless they wanted to get creative and bind tops to the ones that dont already have one, and bind a laminate back to the ones that have a top already.
really i know they wont make recessed back covers, just impracticle. how big is the demand? i know i'm not the only one that doesn't use 'em.
then new bodies will have all diferent specs from the old, longer neck screws, ect. ect. and if they did it on the current bodies there would need to be a disclaimer the the trem block is not garenteed to fit, they'd need to make a list of compatable bridges, many of which are oem bridges.