Consider that groff itself is somehow like plainTeX. You may need a macro package for creating documents. But traditional macro packages do (AFAIK) not provide TOC, index, cross references *compared to LaTeX*. Up to now I did not test the MOM macros (http://www.schaffter.ca/mom/mom-01.html) but likely they have this functionality. But it is also not hard do write a script (I suggest using perl) for that.
So either you use groff with MOM or you may need to write some simple scripts... (TOC itself actually doesn't need a script, the ".tm" request is sufficient). OT question: What is your issue with LaTeX? Carsten