Are you asking specifically about voltage controlled amplifiers...or are you really asking about desk automation, which can be done other ways besides the use of VCAs....?
Assuming your asking about desk automation...
I had a basic fader/mute setup for my desk, but it was not built-in, rather it was an add-on system.
To be honest...I used it a few times and then just went back to manually moving faders.
On a the huge input desks that are 10' long...it's probably a necessity. On smaller ones, not really.
Now if you're talking about a desk that has more than just fader/mute automation, like where you can have the EQs and Auxes, etc....then that would might be nice even on a smaller desk...but that's probably going to be an $$$ desk.
These days, since I run a hybrid DAW/outboard setup...I pretty much get my individual levels set in the DAW per track...that way, on my console, I'm rarely touching the faders once I get them where I want them.
Not to mention, I can run volume automation on the DAW tracks too...but I never do that, as most of my tracks are sliced into lots of sections and then I just *set* the volume for that section.