@noseman : ok fair remark, how can i convince you?
i think i can only explain this with telling you what's happening in my line of work (archiviz for architecture competitions)
10 years a go it was normal to make 2 or 3 images for a competition
nowadays they (the architect but also the competition-organisation) demand 10 to 20 images.
a good exemple is this project http://www.bmd3d.com/bmdpages/bmdNMM.html
as you can see this is a complex project with lot's of objects and a certain level realism.
Typical for these competitions they want large images : double page A3 bookworks are a standard
plus they wanna be able to show details of those large images because they wanna explain certain elements of the design
So the images are always rendered at 5000 to 8000pixels, = rendertimes on one computer are high: 4 to 18hrs
and putting the renderings in a batch is handy when you have to do 10 images
Of course we make previews and double-check if any furniture is floating above the floor etc...
But time, deadline-stress and of course being a competition: there are last minute changes in the design etc... mistakes happen.
In every project there are images we have to re-render because i forgot to put the lights back on, etc...
(every camera has his own sun, background plane, set of lights, set of trees etc... )
Seeing the rendering progress (like with the renderbatch) helps prevent these mistakes
Also things like material ID & Object ID or re-render just a part of the image are very useful to us
Another typical error why re-render an image is AA & GI
When the 1 on 1 preview is rendering you see you should have used a higher GI or AA
People also ask me why not use the stage-object and animate the camera, of course sometimes we use this method
but most of the projects are too complex and big to start doing this kind of "stage object animations"
to many things change with every camera, it takes to much time to make the animation
Does the above explain to you why this is for archiviz work an important feature ?
i have no idea if it's useful in other area's of 3dwork but it's nothing new, it was possible with the renderbatch until R13
i don't think there many people not even maxon against a full preview in renderqueue,
the question is more how important is this for your work