If a repro is 100% unauthorized, then yeah, you may as well pirate since goodness knows who your money is going to with those repros. There's often a fine line, if any line at all, between repros and bootlegs, and a lot of these "repros" coming out of China are only different from traditional Chinese bootlegs in that they're not contemporary with the original, official release. And when you're talking Chinese bootlegs, you very well may be funding organized crime. I think a lot of people are inclined to be dismissive of that, since they can't picture their niche hobbies like retro games, anime, soundtracks, etc. having anything to do with literal mafias, but those people will try to make a buck wherever they see one to be made, even if it means selling "nerdy" goods.

On the other hand, you've got partially licensed repros like these from LRG. They're not licensed by the hardware manufacturers, since a company like Nintendo obviously isn't in the business of putting out new releases on long ago retired hardware, but they're licensed and authorized by the publisher of the IP. In this case, your money actually does reach the people who made the game (or published it, at least), so that's preferable over pirating. (Granted, that's also preferable to the publisher over people buying secondhand copies of the original release, but when you put out a physical product, you have to expect reselling.)