Although I personally don't mind how the current release works, I do have sympathy for Herbo's (and others) concerns.
Perhaps part of their frustration is that what they are proposing (keep the settings in the render window but don't start the renderer automatically) seems like a good solution, without compromising on the advantages of the current design of having the settings integrated in the frame buffer. It also (perhaps wrongly) sounds like relatively simple to implement. But maybe it's waaay harder than it sounds, and is that also part of what's holding you back?
It's been awhile since I've used it, but I believe this is the way Thea Render worked. The full render dialog box would comes up every time, but it would only begin rendering if you wanted it to. This made sense and was necessary for a non realtime renderer, but I think the same principle could apply with Enscape. If I had to guess, the vast majority of Enscape users won't have a problem with the way 3.0 is setup currently, but a loud and frustrated minority will. Most of my models aren't large enough to present an issue, but I've had some in the past that are, for which I've had to turn the render settings down and switch to White mode in order to get the model to load succesfully. It's a real issue and deserves attention. It seems to me it would be easy enough to add a check box, similar to the RTX dialog now, which you turn off if you don't want Enscape to automatically begin rendering on startup. Most users will never mess with it and it will continue to work just as you've designed it. For the small minority that do need it however, it will ensure Enscape continues to be functional. Win win.