Why no navigation bar customizations? topic

These are pretty standard on just about every ROM out there for pretty much all phones since Jelly Bean, and yet we still dont have the ability to add in more nav buttons or change around the order of them or anything on a single Nexus 6 ROM. We just barely seem to be getting the ability to change the height and I even saw one ROM that could change what happens on long press to one of the buttons. Yet no significant customization for even moving around the order of the 3 stock buttons. Do we have some issue on the N6 that is causing developers to not be able to implement this feature?