I think these VCA faders are more useful than the first looks.
For example, what i have now in 7.5:
I’m arranging a song for a client who has another mixing engeneer. All my 10 strings vsti are routed to the group channel. I have some rough EQ and saturation on the group just to show how approximately it all can sound when mixed. When i need to automate all strings volume, of course i just automate the group volume, not 10 tracks. Same with backing vocals, guitars etc.
But then i need to batch export everything to the the person who will mix the song. If i batch export every track, what happens to everything on a group level? It’s all gone. Mixing guy surely doesn’t need my EQ and saturation, but string volume automation is crucial, i planned it carefully while arranging - i gotta have that in the stems. So in 7.5 the only thing i can do is render each channel individually passing through the group, so the group automation affects it.
But if all that automation was recorded on VCA fader which directly affects the slave tracks’ volume, batch export will keep these chenges. This is a small thing, but it can save me like 40 minutes of exporting. And exporting is something i hate))
Another useful scenario is:
Let’s say i have many many guitar tracks. Clean guitars, edgy crunch guitars, power distortions, counterparts, arpeggios etc. And i want to route them to groupes depending on their character. “Distorted sustains”, “Edgy transients” and “Soft guitars”. “Distorted” will get some group de-essing, “Edgy” i will compress, and “Soft” need some spatial enhancements. But when it comes to volume automation, i need to group them like “Verse Guitars”, “Chorus Guitars” and “Counter Parts” which not necessarily match those routing groupes. And the only thing i can do is linking, but this link/unlink thing is not so very practical for me. And now with VCA fader i can have multichannel volume automation that is independent of the routing. That is lovely.
Another one:
Client comes and says “i wanna ride the vocals myself”. I have my automation done and don’t wanna delete it, because we will probably return to my version in the end 
now i can just give him a VCA fader, which keeps my channel automation intact, and can be disabled later.