> Wouldn't it be easier to try to obtain the original source code? Or has that been lost and all that's left is a blob?

Define easier? There is virtually no incentive for a game studio to release their original source code. Studios are running on already tight enough margins as it is with one lackluster release being enough to doom a company to oblivion.

Unless you have a method to completely reorient capitalism away from the idea of intellectual property then painstakingly reversing the C code from MIPS assembly will always be the easier path.

Remember too, that we are on Hacker News. Only a tiny sliver of the population, in some cases just one or two people, cares about the source code. Not worthwhile for a studio to release the code just to satisfy a couple of nerds. What is the upside? Unknown. Downsides? Numerous.

Almost all instances of source code being released have come from small studios or individuals who are ideologically motivated, and are otherwise independently successful. John Carmack / Id Software comes to mind.