I'm agree with The Hood. The main problem with old stuff released before going open source is that pakset maintainers don't have permission from the author to release the stuff under a open source license (pak128 is a good example of this problem) thus everything they can do is try to put in contact with the author.
On the other hand, nothing prevents you from creating a decompiler, in fact that tool already exists and it's used by some developers, but if you really want share your creations, release the sources instead of trying reverse engineering. In fact, if you put in contact with the author and request the sources, I bet most of them will share their work with you.
Reverse engineering is not evil but imho, respect the work and wishes of others goes first, at least in this case.