Either to teach programmers something (this won't, it's re-hashed Wolf3D);
Hmmm. So because the game content is supposedly not original, you cannot learn from it's source code? If you're really a programmer you should know that you can have ingenious programming in a bad game and the other way round.
but the engine is hopelessly out of date
It certainly is. But do you know how game programmers start out? With Tic-Tac-Toe, Tetris or the like. Everyone has to begin small. No one - no matter how talented - can jump right in coding a 3D engine with all that nifty stuff that we have nowadays. Looking at the source code of a professional game can help newbie programmers - if only to see in what way the game was structured. Never mind the graphics stuff - seeing the central game loop or the way in which the player data is structured can be a big help.
Having said that, reading the ROTT source code is probably not the way to learn game programming for inexperienced programmers. As "gamespysux" has described, games in those days did quite a few things that can be considered "inelegant" or even "bad" (by some standards) because speed was a major problem back then. Looking at assembly and self-modifying code will not help a complete newbie much. On the other hand, a more advanced programmer who is, for example, trying to get his little side-scroller to run well on his gameboy advance emulator may find those old techniques instructive.
I guess it all boils down to the old phrase: "Everything's useful for somebody". If you can't find a use for the source code that's fine. But someone else might.
[Edit: typo]This comment was edited on Dec 20, 19:51.
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