Wow, old thread!
I was wondering what was new about
Doom 3 now. Or
Doom 4 was in the works (no way!)
JHuschke, there's a site that has all the transcriptions and captioning for
Doom 3. Granted, it's not a modification ingame, but it has everything you want to read on there.
Welcome to Doom3[CC]
If you want to take it up with someone, take it up with ID software personally. But
Doom 3 is 5 years old, that's probably why there aren't any subtitles. It was low-key at that time.
Games nowadays seem to come with subtitles much more frequently. I think it's due to the fact that they start releasing internationally, so it's handy to have the extra subtitles available in other countries to cheapen the need for audio dubs.