Hi
@Pvtryanww2
It's a question of there being a market for it, and someone having the vision to see the market, and the money to invest to get the returns. Capitalism 101.
Until the 1990's there were nearly no reproduction parts for WW2 jeeps. This was partly because there were still original parts if you could find them, and parts for French made M201 jeeps fit if you weren't bothered about originality (Incidentally, the jeep coming off the beach in SPR is a Hotchkiss M201, not a Willys MB).
Body parts started to be made in the Philippines, because of the traditional Jeepneys there, and various companies in Europe, and I guess the US started to import them. The early bodies were poor copies, and thin steel, but when it was realised that people would pay for good copies, the quality improved. As the other original spares dried up, then it became worthwhile making reproductions.
About the year 2000 I visted a dealer called Reomie BV in Holland. They had built a Willys MB out of 80% reproduction parts, and at that point told me the following year they expected to build a Ford GPW, and within a couple of years the first 100% reproduction vehicle.
There will never be a market the size of WW2 jeeps. For a start they only made a tenth of the number of bicycles. However that would not necessarily stop someone producing parts and cornering a small market.
You're a young guy who is interested in WW2 and bicycles, you have contacts in the reenacting world, you have the information WW2 bikes we provide gratis here. Perhaps this is your opportunity to "step up"? It would be tough and risky, but you'd be attempting to achieve somehing different, something you enjoy.
I wish you the best of luck if you do decide to.
Best Regards,
Adrian