>>716239295Decompilation takes time, resources, and knowledge, something that cuts into a bottom line. It can take several years on end for hobbyists to decompile a single old video game, and no major company on this earth has hobbyist autists like what the Sonic community has to offer to cut that time in half. Plus I can just about assure you the efforts for decompiling something simply don't have any company stooges lying around to try; it's a very particular set of information, breaking down an old game's code tit for tat into something a modern OS and CPU/GPU can properly hash out.
Everyone that goes "Just go find an old copy, you have the code, bam!" genuinely does not understand what it actually takes to get that code and salvage it into something that doesn't need an emulator, never mind that corporations won't put aside the money for it. The rare exceptions you get are shit like the Mega Man Legacy Collections starting from the Zero/ZX side of things that give you native ports of the respective games, and that's probably because Capcom internal managed to keep their old code around for those games specifically.