While I'm not wholly against the idea of it, I am sympathetic to production not going with an all vintage replica. It's something from someone's collection, essentially a one-off, and it may or may not be insured, and would have to be if it were on set. That's not even considering it being used as a primary hero prop, but using it for reference to make 3D printed copies of and it being passed through various departments; I can see why something like the MR worked its way on set. Sure, they're rare now but nothing compared to an all-vintage, real world parts Kenobi hilt, which a single component of costs vastly more than an MR. Like, down-payment-on-a-car, or mortgage-payment more.
A MR may not be fully accurate, but it's functionally close enough and it maintains a continuity on-screen from RotS; throw on a Roman's Empire emitter to have an ANH element and it's a job done. There are copies of MR's out there (even replicas of MR's) and Roman's keeps a steady supply for the most part. From a production stand point, it certainly makes a lot more sense the route they went more than not.
