Adding a tow hitch to every stock vehicle is a good idea, but considering that the tow hitch first has to be added in a 3d editing program like blender, and then be fully Jbeamed. It is for a low experienced person not that easy to just add a tow hitch. However, because of the fact that the vehicle designers of BeamNG have a lot experience with this, they can add this to a vehicle in a matter of minutes.
I believe the tow hitch model is in "vehicles\common", the only thing you'd need to do is do the jbeam.
Why do people suggest ideas in the mod's section? There is literally a place on the forums called Ideas and Suggestions, so please take your ideas and suggestions there.