Jeremy and Jinger aren't featured in the trailer, true, but they could still make an appearance - the trailer does have a shot of Jinger, from archival TLC footage. 

If they aren't in it, well, this could be because Jeremy and Jinger didn't want to be interviewed/filmed, or demanded money for this, but I find that unlikely - the two of them have made a huge, huge point of trying to remain F list celebrities, and Jinger gave a number of unpaid interviews this year. I think it's more likely that the directors/producers looked at the footage of Jeremy and Jinger and decided it just wasn't entertaining enough to include.  

There's also the related issue that Jeremy tends to come off as very condescending/arrogant on camera, which would work well if this was an anti-MacArthur documentary, but since this documentary apparently plans to present Gothard and Jim Bob Duggar as the villains, it might be a bit distracting.

Regardless, these two are the only family members guaranteed to receive some sort of financial benefit from this, in the form of automated "recommendations" for their books from the Amazon algorithm - advertising that they don't have to pay for.