Quoted from rubberducks:
Unlike AFM and MB, original MM values now once again hugely eclipse MMr values in Europe, looks like they do in the US too. That tends to suggest that people aren't nearly as satisfied with MMr as the subsequent titles, and that there's significant scope for them to sell a lot more of an upgraded title.
It seems like originals still carry a higher value than remakes. Some people will always pay a premium (although certainly smaller than pre-remake) for "originals" (except all the replaced art, boards, PFs, mechs and sometimes even cabs, lol) of all those titles because they believe that they'll last longer, play different, are more customizable, or maybe they just NEED Williams logos... who knows?
The genius of making an "LE upgrade kit" is that it will/may satisfy MMR LE owners and free CGC to do an "MMRR" (or more like an MMR SE) without screwing over their LE base. It's not about just grabbing that cash (although I'm sure they will find some profit) but maintaining the channel and bringing MMR up to the current line standard.
Obviously doing an MMRR LE would piss 1000 people off royally... and I know alot of people who are buying matching CGC LE numbers and would probably just stop if that went down.
SO they make 1000 of the LE upgrade (at most) and call it done. Congrats you early adopters, your LE is in line with the other LEs. Then when they start making MMR SEs they make a small "SE upgrade kit" since the parts will be on the line.
...of course they're basically selling an "MMR Classic" for 8K right now so their motivation might not be very strong, lol.