I know why we couldn't just drop it in at the moment; our transmission model needs a bit more work for that. We could drop it in as is but then you'd all be complaining you can't stall and don't need to clutch to change gear. What I don't know is why the designer or producer didn't want me to add it, then I could have made all the necessary improvements. Be happy I at least took the liberty of making neutral available to sequential manuals, before it was only selectable if you had an H shifter.
If enough people ask for it after release, no doubt they'll ask me to do it for the next game. They're very focused on the casual gaming market first, sim racers second, so things like this can get left behind. A large portion of the dev team (and Activision's QA, you should see the bugs I get!) are just into games, rather than being into racing sims or cars at all. You can't blame them for not having the interest but there's not a lot you can do about it apart from pointing things out.