i wasn't thinking about this in legal terms; yes, it's all in the code and could theortically be used, but the texts and even map names talk of hell-spawn and hell and are specific to DOOM's original story, adapting these same text strings to another story (especially if it's not about demons invading from hell) might not work as well as if there's greater freedom in putting things together based on a new story (the two stories presented up to now speak of aliens but not demons, not that these are definitive). furthermore i had things like fredrik's very cool replacement for the chainsaw in mind; could that be called a chainsaw (as in 'a chainsaw! find some meat!'); if not, the text should change. and think about (ultimate) DOOM's texts, they mentions hellish stuff and specific locations relating to the original story even more than DOOM II, and the map names are completely hellish in some instances and wouldn't fit with a less 'hellish' approach
in the threads about the iwad's name i've been reading about a concern to deviate from id's original theme as to not create an enmulation or direct replacement of DOOM but instead tend towards a new feel, different game 'universe' that runs with DOOM's GPLed engines. using id's text strings doesn't leave much freedom for creting something sufficiently different.
saint_of_killers: yeah, but the names in small type appearing with the automap are hardcoded
it would be a matter of weighing between having to work with a DEH patch and having more freedom to create something less similar to the overall idea of DOOM (without ever touching the gameplay, which is the genuine engine feature), or leaving aside the patch but having to adapt the resources closely to the hardcoded strings