Propose:
Consistency in Layouts: Aligning the track views, chord views, piano roll, mixer, and other layouts between BB and RB could reduce confusion for new users.

Reducing Learning Cycle: A consistent GUI would help new users become productive more quickly, as they wouldn't have to learn different interfaces for similar tasks.

Boosting Productivity: By minimizing the learning curve, users can focus more on creating music rather than figuring out the software.

User Transition: Users who start with BB and then move to RB would find the transition easier if the interfaces are similar.
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I understand your thoughts and it makes sense going from BB to RB. However, you have a lot of assumption that may not be the case.

1) Which is correct? Which is better? Should both change? Are there better models in the music software universe?

2) New user, when I start with a new user I introduce them to the plugin. Coming from the DAW world it keeps them in their workflow and only adds the steps to generate backing tracks. Should BB copy the plugin? Some say yes, can you drag multiple tracks in BB?

3) I then introduce them to BB, where you can do Partial gens, Playable real tracks and the Mutli Library browser of musicians.

So, you sese it depends on where they are coming from and what is the interest in the PGM feature.

Studio One (latest version), Win 11 23H2 , i9 -10940X 3.3 GHz, 32GB Mem, a 4K 40" monitor, PreSonus Studio Live III Console as interface/controller. secondarily test on Reaper, Cakewalk, and S1 on Surface Pro 3 Win 10 (latest versions).