> The ROM scene has always been a grey (verging on black) area when it comes to IP
Speak for yourself.
There are two scenes: The binary modder scene, where people retro-fit vendor-created and provided firmware-images with their own modifications. Commonly referred to as "Photoshop ROMs". This scene is clearly grey at best.
However, there is another scene: The one based on AOSP source and derivates of it. This scene lives on Github and similar places where open source is shared and reused freely, as intended.
This is driven by serious developers and focus is on doing things cleanly, properly and reliably.
Most successful and widely deployed ROMs (like Cyanogenmod) are based on this scene, and there is nothing grey or remotely shady about it.