I can understand wishing for new features and it taking so long, been through years n years n years of that with RB frown
I remember asking for solo buttons for RealBand
https://www.pgmusic.com/forums/ubbthreads.php?ubb=showflat&Main=19003&Number=122728&page=all and the pic showed a floating mixer 6 years before it was added to Biab.
Volume automation for non destructive volume editing (like that's just been added to Biab).
The one that took the longest was sending VstTimeInfo to the virtual instrument like EZDrummer/Keys to sync playback that took like 10 years.

After all that I gave up on RB as I could not use it in a professional environment working with artist to create tracks for their songs was too stressful and time consuming.

The main issue why it's not popular is the generate time, if it was as quick or quicker than Biab it would be more popular thus having more development time spent on it, but now Biab is being made more like a DAW simply because of the generate time that users like. They don't like going back n forth to their DAW and would rather do it all in one app.
Jeff spent a lot of time on RB but now I think he is maybe working on Biab mostly.
Most users would be creating their song up quickly in Biab then off to their smooth non destructive editing DAW.

I can think of so many things to make RB better like non destructive editing and instant generate and playback (even quicker than Biab) from RT RD source files using internal code rather than getting bbw2 in the background to generate tracks into RAM then render down to wav and put them in the RB temp folder.
No one has spent more time pushing for and wanting RB to be better, but it's just not practical. I have spent 13 years digging deep into it all and see how it all works and the best example is the Biab Track Injector for Reaper . This is the way it all needs to work in this day n age. This way allows for a Live Arranger version of Biab maybe using the Plugin Standalone.
That's why I'm still here even though I have given up many times stupid me gets back in the ring for another swing as I would like to see it all through and become a reality because of all the time and effort spent on it.
If this was done to RB back in 2008 it would be the leading one now and I would not even be here !, but that horse has bolted.

RealBand will still be here for a while with a little tweak added now and then but the future would have to be in the BBPlugin/Standalone as it's a fresh start and looks professional but just needs the internal generate code rather than the slow asss bbw4 route. I can see the Plugin Standalone becoming the new Biab DAW down the track.

Kristal Audio Engine (Studio One) doing non destructive editing back in 2004 ! it just references the WAVE, AIFF, FLAC, OGG Vorbis without creating new wav files. See it has solo mute buttons. Download Kristal AE
Reaper also on it's release back in 2006.

This is Biab 2007 with Kristal 2004, look where Studio One is now compared to Biab.