I’m not a ROM developer but I had a Motorola phone and I could see why maybe it would have been ignored for custom ROMs, it had a few non-standard features that were great when using the phone, but I think a pain to support, it had a little touchpad in the bottom center that you could swipe your thumb on to do ‘gestures’ in android like back, recent apps, home, etc. I really liked it but its another weird feature you have to keep working when you’re supporting the phone after the manufacturer stopped providing updates.