I totally agree! I'd love to see the source code for the original Rollercoaster Tycoon, for example. From what I understand, it's 99% assembly with a few parts in C to handle media. It would be awesome to try to grok that!
Reading foreign assembly isn't that bad unless it is being intentionally obscured. It definitely takes time to decipher things but at the same time you really learn what's going on :)