You might have your reasons, but sorry if I disagree here.

Then the recording interface's power consumption would be so high that it can no longer be operated USB bus-powered.
Not to mention that the Babyface would no longer be as compact as it is now.
And how much should it cost, then who would still buy it?

The RME recording interfaces are not designed to provide you with a DAW controller. There is more of a connection between the recording interface and TotalMix FX.

It's better to focus on the things that are important for a recording interface, like RME does.

All these DAW controls are a matter of taste, many people don't need them or get what they need separately. That is a topic in itself and should not be mixed up with the recording interface.

What you want or suggest is similar to a compact hi-fi system. But as we all know, compact systems mainly consisted of many compromises, with individual components you were always much better off and the quality was also better.

That would also bring a complexity into the recording interface that, in my opinion, has no place there.

And in direct comparison. Compare the technical implementation of both interfaces and the expandability. Then you will see that you are in a much better position with the Babyface Pro FS. The focus is on delivering a very compact professional device of high quality with the essential functions for recording.

Not for me either.